You can check your subscription information and manage it via this link: https://perfectbody.me/client/login
You can always access this page by clicking Manage Your Subscription at the very bottom (footer) of the Perfect Body homepage.
Log in with your account details, username, and password. You will be able to see the status of your subscription and cancel it if you wish.
If you have purchased your subscription via Google Play, you'll find cancellation instructions in this article.
If you subscribed via the App Store, please follow the instructions here.