Buying credits from Ashley Madison is not subscription-based. You will remain a full member providing you have a positive credit balance in your account.
To cancel any automatic re-billing features (eg. Prime, Priority Man, etc.), access your account on desktop or mobile web, and:
Log in to your Ashley Madison account using your case-sensitive username and password;
Click on the three horizontal pink lines [☰] in the top-left corner;
Then on Settings;
Then Account; and
Here you can access information about your credits, purchase history, auto top-up, and active subscriptions, and can make the necessary adjustments.
Unfortunately, you cannot cancel subscriptions using the Ashley Madison app.
Very important: Effective immediately, fraudulent cancellations now result in immediate account suspension, investigation, and possible legal action. Fraudulently disputing transactions through banks/credit card issuers may be dealt with to the fullest extent of the law.