Terms of Service

Article 1 (Purpose)

These Terms set forth the terms and procedures for using the services provided by DAYLAB (hereinafter referred to as the "Company"), namely HSK 4 (an HSK Level 4 study mobile app), hereinafter referred to as the "HSK 4" or the "Service"), and the rights, obligations, and responsibilities of the Company and users.

Article 2 (Definitions)

• "Service" means the HSK 4(HSK Level 4 study mobile app (iOS/Android), related websites, and supplementary services provided by the Company.
• "User" means a person who uses the Service pursuant to these Terms.
• "Content" means all information provided within the Service, including questions, explanations, images, UI design, and software.

Article 3 (Effectiveness and Amendment of Terms)

• These Terms become effective when posted on the Service screen or notified to users by other means.
• The Company may amend these Terms within the scope not violating applicable laws and will notify users in the Service from 7 days before the effective date of the amendment. However, important changes unfavorable to users will be notified from 30 days before the effective date.
• If a user continues to use the Service after the effective date of the amended Terms, the user is deemed to have agreed to the amended Terms.
• If a user does not agree to the amended Terms, the user may stop using the Service.

Article 4 (Provision of Service)

The Company provides the following services.

• HSK Level 4 Exam preparation question practice
• FSRS-based spaced repetition learning
• Learning status heatmaps by subject
• Practice mock exams
• Incorrect-answer note
• Cloud synchronization of learning data and cross-device access upon member login

Article 5 (Membership registration and account management)

• The Service may be used without membership registration. If users wish to use member-only features, such as cloud synchronization of learning data, they may register as members through social login (Apple, Google) or email verification.
• Users must provide accurate information when registering as members and must not use another person's account or authentication information without authorization.
• Users are responsible for managing their own account and login methods and must notify the Company immediately if they become aware of unauthorized use of their account.
• Users may request withdrawal of membership (account deletion) at any time through Settings > Account in the app. Upon withdrawal, member account information and synchronized learning data stored in the cloud will be destroyed without delay. Details of the items and procedures for destruction are governed by the Privacy Policy.
• Users may at any time, in [Settings > Account Management] in the app, (1) delete only this app's data or (2) delete the entire DAYLAB integrated account.
• Account deletion is separate from cancellation or refund of a paid subscription, and subscription cancellation must be completed separately through the App Store or Google Play.
• The account system may be shared with other DayPrep learning apps operated by the Company, and learning data for each app is managed separately by app.

Article 6 (Modification and Suspension of Service)

• The Company may modify or suspend all or part of the Service for operational or technical needs and will notify users in advance within the Service in such cases.
• Prior notice may be difficult for service interruptions caused by force majeure, such as natural disasters, war, power outages, or system failures.
• If the Company permanently terminates the Service, it will notify users at least 30 days before the termination date.

Article 7 (Obligations of Users)

• Users must use the Service only for personal learning purposes.
• Unauthorized reproduction, distribution, transmission, or publication of the Service's Content is prohibited.
• Interfering with the operation of the Service or using it by abnormal means is prohibited.
• Reverse engineering, decompiling, or disassembling the Service's software is prohibited.

Article 8 (Intellectual Property Rights)

• Copyrights and intellectual property rights in all Content provided in the Service, including questions, explanations, UI design, and software, belong to the Company.
• Users may use the Service's Content only for personal learning purposes and may not use it for commercial purposes or provide it to third parties without the Company's prior written consent.

Article 9 (Restriction of Use)

• If a user violates obligations under these Terms, the Company may restrict or suspend use of the Service.
• When restricting use, the Company will notify the user in advance of the reason and restriction period. However, if there is an urgent reason, the Company may notify the user afterward.

Article 10 (Push Notifications)

• If a user consents to receive notifications, the Company may send push notifications, such as learning reminders, review notifications, and service notices.
• Users may opt out of receiving notifications at any time through notification settings in the app or device operating system, and notifications will stop when they opt out.
• The information processed for sending notifications and its retention period are set out in the Privacy Policy.shall be governed by.

Article 11 (Paid Services)

• The Company provides the following paid products (hereinafter referred to as "Premium") within the Service.
• With a Premium subscription, users may access additional features such as ad removal and unlocking all questions.
• The types, prices, and details of paid products can be checked on the in-app purchase screen, and the Company may change them after prior notice.

Article 12 (Payment and Auto-Renewal)

• Payment for paid services is made through in-app purchases in the Apple App Store or Google Play Store.
• Auto-renewing subscription products (monthly and 3-month) renew automatically under the same conditions unless canceled at least 24 hours before the subscription period expires, and the fee is charged to the registered payment method at the time of renewal.
• To cancel auto-renewal, users must cancel directly in the subscription management settings of the App Store or Google Play. Deleting the app alone does not cancel the subscription.
• Lifetime access is a one-time purchase and does not auto-renew.

Article 13 (Refunds and Withdrawal of Subscription)

① Period for Withdrawal of Subscription

Pursuant to Article 17(1) of the Act on Consumer Protection in Electronic Commerce, users may request withdrawal of subscription within 7 days from the payment date for the paid service.

② Grounds for Restricting Withdrawal of Subscription

Pursuant to Article 17(2)5 and Article 17(6) of the same Act, withdrawal of subscription is restricted in the following cases. The Company clearly notifies users of this fact through these Terms and the payment screen and obtains user consent before payment.

• Where provision of digital content has begun — withdrawal of subscription is restricted from the time any paid feature is used even once, including quiz solving, mock exam taking, FSRS review card use, or viewing the incorrect-answer note.
• For auto-renewed recurring subscriptions, a refund is available only if the request is made within 7 days from the renewal date and no paid features have been used after renewal.
• Lifetime access is refundable within 7 days only if no paid features have been used after payment.

③ Refund Request Channels

Because paid service payments are made through the in-app purchase systems of the Apple App Store and Google Play, refund requests are also processed through each platform.

• Apple App Store: reportaproblem.apple.com to request a refund directly
• Google Play: Play Store > Subscriptions or payment history > Request a refund
• In case of dispute: contact@daylab.dev to contact

④ Refunds Due to Reasons Attributable to the Company

If a service failure occurs due to reasons attributable to the Company, users may request a refund or compensation from the Company, and the Company will handle it within a reasonable scope.

Article 14 (Disclaimer)

• Except in cases of the Company's intent or gross negligence, and to the maximum extent permitted by applicable law, the Company assumes no liability for the following matters.
• Questions and explanations provided in the Service are for learning reference only and do not guarantee passing the exam.
• The Company assumes no liability for service interruptions caused by force majeure, such as natural disasters, war, power outages, or system failures.
• The Company assumes no liability for loss of learning data stored on the device due to the user deleting the app, initializing the device, or similar actions.
• Nothing in this Article excludes or limits the Company's liability that cannot be excluded under applicable law.

Article 15 (Age Restriction)

• The Service is intended for users aged 14 or older.
• The Company does not collect or process the personal information of children under the age of 14 and does not permit children under the age of 14 to use the Service. If it is confirmed that a child under the age of 14 has used the Service, the Company will destroy that user's personal information without delay and restrict use of the Service.

Article 16 (Governing Law and Dispute Resolution)

• These Terms are interpreted and applied in accordance with the laws of the Republic of Korea.
• Disputes between the Company and users related to use of the Service will be subject to the Seoul Central District Court as the court of first instance.

Article 17 (Revision History)

If you need a previous version, contact@daylab.dev please request it at . When these Terms are amended, the Company will provide prior notice from 7 days before the effective date pursuant to Article 3 of these Terms (30 days before the effective date for material changes unfavorable to users).

Supplementary Provisions

• Business Name: DAYLAB
• Representative: Dasong Sim
• Business Registration Number: 401-23-55110
• Mail-Order Sales Business Registration Number: No. 2026-Seoul Seocho-0911
• Address: 10, 11, 1F, 91 Baumoe-ro, Seocho-gu, Seoul, Republic of Korea
• Tel: 0505-007-7703
• Email: contact@daylab.dev

These Terms of Service take effectAugust 18, 2026..

© 2026 DAYLAB