Legal analysis: it belongs to service contract. You establish a service contract relationship with the gym, buy a fitness card, etc. The gym provides services for you.

Legal basis: Civil Code of People's Republic of China (PRC).

Article 119 A legally established contract is legally binding on the parties.

Article 533 Significant changes have taken place in the basic conditions of a contract after the conclusion of the contract, which could not have been foreseen by the parties when the contract was concluded, and are not commercial risks. If it is obviously unfair to one party to continue to perform the contract, the adversely affected party may renegotiate with the other party; If negotiation fails within a reasonable time, the parties may request the people's court or arbitration institution to modify or terminate the contract. The people's court or arbitration institution shall, according to the actual situation of the case, modify or terminate the contract in accordance with the principle of fairness.