PSA Unless you opt out MoviePass may automatically re-enroll you

Because you agreed to it in their terms and conditions terms and conditions, when you signed up;

2.11.

(i) MoviePass offers three types of subscriptions, month-to-month, three months and annual. MoviePass will bill upon subscription to the service and then will bill based on the date you receive your card pursuant to the terms of your subscription, unless either party seeks to terminate the agreement. You must cancel your membership before it renews in order to avoid billing of the next month's membership fees to the payment method you provided to us. THERE IS NO REIMBURSEMENT FOR EARLY TERMINATION OF A MEMBERSHIP. If you do not contact us prior to the billing date, your card will be charged and termination will occur at the end of the next billing cycle.

It's no different to any subscription service, like Netflix, Spotify, Amazon Prime, Playstation Plus, etc. You sign up, and it auto-renews after each period unless you contact them to cancel it.

/r/movies Thread Parent