A btwb Gym Subscription is made up of different pricing tiers. Gym are charged automatically each month for the appropriate tier based on the number of members in their btwb gym. Gyms will automatically move up and down the pricing tiers as they add and remove members from their btwb gym. All new btwb gyms are granted a 30 day free trial.
If gyms would rather pass the cost onto their members, btwb also offers a Member Pays subscription that makes each individual member associated with their gym responsible for their own subscription. Those subscriptions are billed at the individual pricing rate ($7.99/month or $87/year).
Visit How Do I edit My Gyms Subscription? for details on changing your gym subscription.