Data Deletion Policy
Mastery — Adaptive Vocabulary Mastery System
Effective Date: February 23, 2026
1. Overview
This Data Deletion Policy describes how you can request the deletion of your personal data from Mastery and what happens when you do. This policy applies to all users, regardless of location, and is designed to comply with the GDPR (Article 17, Right to Erasure), UK GDPR, CCPA/CPRA (Right to Delete), LGPD, and other applicable data protection laws.
Data Controller: Valentin Seehausen, Germany
Contact: privacy@mastery-app.com
2. How to Request Data Deletion
2.1 In-App Account Deletion (Recommended)
You can delete your account and all associated data directly from the app:
- Open Mastery
- Go to Settings > Account > Delete Account
- Confirm the deletion
This initiates immediate deletion of your account and personal data, subject to the retention exceptions described below.
2.2 Email Request
You may also request data deletion by emailing privacy@mastery-app.com with the subject line "Data Deletion Request." Include the email address associated with your Mastery account so we can verify your identity.
We will acknowledge your request within 7 days and complete the deletion within 30 days, in accordance with GDPR requirements.
2.3 Partial Deletion
If you wish to delete specific data (e.g., certain words, learning history) without deleting your entire account, contact privacy@mastery-app.com with details of what you would like deleted.
3. What Gets Deleted
When you delete your account, we delete the following data:
| Data Category | Action | Timeline |
|---|---|---|
| Account data (email, name, auth identifiers) | Permanently deleted | Within 30 days |
| Learning data (words, translations, source sentences) | Permanently deleted | Within 30 days |
| Review history (FSRS data, session logs, card responses) | Permanently deleted | Within 30 days |
| Vocabulary model (Memory Mirror data, stage progression) | Permanently deleted | Within 30 days |
| Kindle sync data | Permanently deleted | Within 30 days |
| User preferences and settings | Permanently deleted | Within 30 days |
| Subscription entitlements (internal records) | Permanently deleted | Within 30 days |
4. What We Retain (and Why)
Certain data may be retained after account deletion due to legal obligations:
| Data Category | Retention Period | Legal Basis |
|---|---|---|
| Payment and transaction records | 7 years from transaction date | German tax law (§147 AO, §257 HGB) |
| Records of the deletion request itself | 3 years | Legitimate interest (legal defense, compliance documentation) |
| Anonymized, aggregated analytics data | Retained indefinitely | Legitimate interest (this data cannot identify you) |
We do not retain any data that can identify you beyond what is legally required.
5. Third-Party Data Deletion
When you delete your account, we also instruct our data processors to delete your data:
- Supabase: Account and learning data deleted from our database.
- RevenueCat: Subscription records are disassociated from your identity. RevenueCat may retain anonymized transaction data per their retention policy.
- Stripe: We do not request deletion from Stripe, as payment records are subject to legal retention requirements. Stripe retains data per their own data retention policy and legal obligations.
- Apple / Google: App Store subscription and transaction data is managed by Apple/Google. You may request deletion directly from Apple or Google per their respective privacy policies.
- Analytics and crash reporting providers: We instruct deletion of data associated with your user identifier.
6. Subscription Cancellation
Deleting your account does not automatically cancel an active subscription billed through the Apple App Store or Google Play Store. Before deleting your account, cancel your subscription through:
- Apple: Settings > Apple ID > Subscriptions
- Google: Play Store > Payments & subscriptions > Subscriptions
Web (Stripe) subscriptions are automatically cancelled when your account is deleted.
7. Backups
Deleted data may persist in encrypted, automated backups for up to 30 days after deletion. Backups are rotated on a rolling basis, and deleted data will be permanently purged as backups expire. We do not restore individual accounts from backups.
8. Irrevocability
Account deletion is irreversible. Once your data is deleted, it cannot be recovered. Your vocabulary, learning history, and progress will be permanently lost. If you wish to use the Service again, you will need to create a new account and start over.
We recommend exporting your vocabulary data before deleting your account (available in the app under Settings > Export Data).
9. Verification
To protect against unauthorized deletion requests, we may verify your identity before processing a deletion request submitted by email. Verification may include confirming the email address on file, confirming recent account activity, or other reasonable measures proportionate to the sensitivity of the data.
In-app deletion (Section 2.1) does not require additional verification, as you are already authenticated.
10. Contact Us
If you have questions about data deletion or need assistance, contact us at:
Valentin Seehausen
Email: privacy@mastery-app.com
We will respond to all inquiries within 7 days.