Terms of Service

1. Scope

These Terms govern your use of the Thuộc Từ app ("the Service") provided by Shijiazhuang Jizhan Technology Co., Ltd. ("We", "Us"). By downloading or using the Service you agree to these Terms; if you do not agree, please stop using it.

2. Description of the Service

• Thuộc Từ is an English vocabulary-learning app based on spaced repetition (the Ebbinghaus memory curve), offering: word books, daily study plans, review sessions, study statistics and a dictionary;
• Advanced features (AI-generated readings/stories, pronunciation scoring, unlimited content) are paid features available under a VIP plan;
• The Service is freemium: basic functions are free with limits; advanced functions require VIP.

3. Accounts

• You may sign in with a phone number (+84), a Google account, or try the app with a device-bound guest account;
• You are responsible for keeping your device and credentials secure; all activity under your account is deemed to be yours;
• Each account is personal and non-transferable; selling, renting or transferring accounts is prohibited.

4. VIP plans, in-app purchases and renewal

• All purchases of VIP plans (monthly / quarterly / lifetime) and coins are processed through Google Play Billing; prices are displayed in Vietnamese dong on the store page;
• Payment is charged to your Google Play account; we do not collect card numbers;
• Subscription plans (where applicable) auto-renew until cancelled. You may cancel at any time in Google Play → Payments & subscriptions → Subscriptions, at least 24 hours before the renewal date to avoid the next charge;
• Cancellation mid-cycle does not refund the used period; refund requests are handled under the Google Play refund policy;
• We may change plan prices and included features; price changes are not retroactive to periods already paid.

5. Content and intellectual property

• All UI, source code, licensed word-book data, artwork and the "Thuộc Từ" brand belong to us or our lawful licensors; copying, modifying or redistributing is prohibited;
• AI-generated content (readings, stories, examples) is provided "as is" for study purposes and may contain errors; do not rely on it as official material (legal, medical, academic);
• Your learning data belongs to you and is used only per the Privacy Policy.

6. Acceptable use

You agree not to: (a) reverse-engineer, crack or automate unauthorised access to our servers; (b) upload content unlawful in Vietnam; (c) abuse AI features to generate prohibited content; (d) commit transaction fraud (including improper refund claims). Violations may result in account termination without refund.

7. Disclaimers and limitation of liability

• The Service is provided "as is"; we do not warrant uninterrupted operation or specific learning outcomes;
• To the maximum extent permitted by law, our aggregate liability to you is capped at the amount you paid for the Service in the preceding 12 months;
• We are not liable for events beyond reasonable control (force majeure, Google/carrier infrastructure failures).

8. Termination

You may stop using the Service and delete your account at any time (see the account deletion page). We may suspend or terminate access for breach of these Terms, with notice except in urgent cases.

9. Changes to these Terms

Material changes will be posted on this page with an updated effective date and announced in the app. Continued use after the effective date constitutes acceptance.

10. Governing law and disputes

These Terms are governed by the laws of Vietnam. Disputes will first be attempted to be settled by negotiation; failing that, they shall be brought before the competent People's Court of Vietnam.

11. Contact

Operator: Shijiazhuang Jizhan Technology Co., Ltd.
Support: support@91word.com