You can only have one drink for free a day, and you must make it clear that it is either on the coupon or in a conspicuous place in the store.

In addition, "the final interpretation right" does not mean "I have the final say", and the final interpretation right is the format clause.

The store did not inform that it violated the contract law.

Article 39 Where a contract is concluded by standard terms, the party providing the standard terms shall follow the principle of fairness to determine the rights and obligations between the parties, and take reasonable measures to draw the attention of the other party to the terms exempting or limiting its liability, and explain them according to the requirements of the other party.

Abuse of the right of final interpretation violates the Measures for the Administration of Retailers' Promotion Behavior.

Article 6 The contents of advertisements and other promotional activities of retailers shall be true, lawful, clear and easy to understand, and vague and misleading language, words, pictures or images shall not be used. Do not harm the legitimate rights and interests of consumers on the grounds of retaining the right of final interpretation.

Article 7 When a retailer carries out promotional activities, it shall clearly indicate the promotional contents in a prominent position in its business premises, and the promotional contents shall include promotional reasons, promotional methods, promotional rules, promotional period, promotional product range and relevant restrictions.