When a user joins a gym on btwb that has a Gym Pays subscription, your individual btwb subscription is automatically canceled upon joining. Since the gym is picking up the fee for its members, individual users don't need to have individual subscriptions. For users with yearly/monthly subscriptions the unused portion of the individual subscription will be canceled AND saved as store credit upon joining the gym.
If you leave the gym and want to continue with your own subscription, you will need to repurchase your btwb subscription. Your saved unused credit will be applied to. your payment.