List your gym.
Two monthly plans. Basic is $29 and keeps a standard place in the directory. Featured is $79, sits at the top, and carries a badge while the subscription is active. Both are billed by Stripe until you cancel in the billing portal.
Payment does not publish the listing by itself. A paid submission waits for review. If it is rejected before it goes live, the refund policy explains what happens. Cancel anytime from manage billing.