Welcome to Lingu Diary. These Terms of Service ("Terms") govern your use of the Lingu Diary mobile application (the "App") operated by LinguDiary Team ("we", "us", or "our").

By accessing or using the App, you agree to be bound by these Terms. If you do not agree to these Terms, please do not use the App.

1. Acceptance of Terms

By creating an account or using the App, you confirm that:

• You are at least 13 years of age
• You have the legal capacity to enter into these Terms
• You will comply with these Terms and all applicable laws

2. Description of Service

Lingu Diary is an AI-powered English learning application that provides:

• Daily English journal writing features
• AI-generated corrections and feedback on your writing
• Learning progress tracking and statistics
• Vocabulary building tools
• Subscription-based premium features

3. User Accounts

3.1 Account Creation

• You must provide a valid email address to create an account
• You are responsible for maintaining the confidentiality of your account credentials
• You are responsible for all activities that occur under your account
• You must notify us immediately of any unauthorized use of your account

3.2 Account Termination

• You may delete your account at any time through the App's Settings
• We reserve the right to suspend or terminate accounts that violate these Terms
• Upon termination, all personally identifiable data is permanently and immediately deleted. Limited billing metadata may be retained in anonymized form as required by Korean commerce laws — see the Privacy Policy for details
• Deleting your Lingu Diary account does not cancel any active Apple subscription. You must cancel separately through Apple ID settings before deletion to stop future charges

4. Subscription and Payments

4.1 Subscription Plans

The App offers two subscription tiers:

• Free: Basic features with limited AI feedback quota
• Plus: Premium features including expanded AI feedback quota, follow-up questions, and progress reports

4.2 Payment Terms

• All payments are processed through Apple's App Store
• Subscription prices are displayed in the App and may vary by region
• Payment will be charged to your Apple ID account at confirmation of purchase
• Subscriptions automatically renew unless auto-renew is turned off at least 24 hours before the end of the current period

4.3 Refunds

• Refund requests must be directed to Apple through the App Store
• We do not process refunds directly as payments are managed by Apple
• Refund eligibility is determined by Apple's refund policy

4.4 Subscription Changes

• We reserve the right to modify subscription pricing with prior notice
• Price changes will not affect existing subscriptions until renewal
• You will be notified of price changes before they take effect

5. User Content

5.1 Your Content

• You retain all ownership rights to the diary entries and content you create
• By using the App, you grant us a limited license to:
  • Store your content on our servers
  • Process your content through AI services for correction purposes only
  • Display your content back to you within the App

5.2 Content Guidelines

You agree not to submit content that:

• Violates any law or regulation
• Infringes on intellectual property rights of others
• Contains hate speech, harassment, or threats
• Includes spam, malware, or malicious code
• Violates the privacy rights of others

5.3 Content Removal

We reserve the right to remove content that violates these Terms without prior notice.

6. AI-Generated Content

6.1 Nature of AI Feedback

• AI-generated corrections and feedback are provided for educational purposes only
• AI suggestions may not always be accurate or appropriate
• We do not guarantee the accuracy, completeness, or reliability of AI-generated content
• You should use your own judgment when applying AI suggestions

6.2 AI Data Processing

• Your diary entries are sent to third-party AI providers (such as OpenAI and Google Gemini) only when you request feedback. The active provider may change over time
• AI providers process your text solely for generating corrections
• Your content is not used to train AI models
• See our Privacy Policy for more details

7. Intellectual Property

7.1 Our Rights

The App, including its design, features, text, graphics, logos, and software, is owned by LinguDiary Team and protected by copyright, trademark, and other intellectual property laws.

7.2 Limited License

We grant you a limited, non-exclusive, non-transferable license to use the App for personal, non-commercial purposes in accordance with these Terms.

7.3 Restrictions

You may not:

• Copy, modify, or distribute the App or its content
• Reverse engineer or decompile the App
• Remove or alter any copyright or proprietary notices
• Use the App for commercial purposes without our permission
• Create derivative works based on the App

8. Prohibited Conduct

You agree not to:

• Use the App for any illegal purpose
• Attempt to gain unauthorized access to our systems
• Interfere with or disrupt the App's operation
• Harvest or collect user information
• Impersonate any person or entity
• Upload viruses or malicious code
• Violate any applicable laws or regulations

9. Disclaimer of Warranties

10. Limitation of Liability

11. Indemnification

You agree to indemnify and hold harmless LinguDiary Team from any claims, damages, losses, liabilities, and expenses (including legal fees) arising from:

• Your use of the App
• Your violation of these Terms
• Your violation of any rights of others
• Your content submitted to the App

12. Changes to Terms

We reserve the right to modify these Terms at any time. We will notify you of significant changes through:

• In-app notifications
• Email notifications (if applicable)
• Updated "Last Updated" date at the top of these Terms

Your continued use of the App after changes constitutes acceptance of the modified Terms.

13. Governing Law and Dispute Resolution

13.1 Governing Law

These Terms are governed by the laws of the Republic of Korea, without regard to conflict of law principles.

13.2 Dispute Resolution

• Any disputes shall be resolved through good-faith negotiations
• If negotiations fail, disputes shall be submitted to the competent court in Seoul, South Korea

14. Contact Information

If you have questions or concerns about these Terms:

LinguDiary Team
Email: support.lingudiary@gmail.com

15. Acknowledgment

By using Lingu Diary, you acknowledge that you have read, understood, and agree to be bound by these Terms of Service.