If you purchased through the App Store
You can manage your subscription, including turning off auto-renewal, for the App purchased through the Apple App or iTunes store following the instructions here.
If you purchased through Google Play
You can manage your subscription for Google Play purchases following the instructions here.
If you purchased through The Tapping Solution directly (www.thetappingsolutionapp.com)
You can go login to view your membership, cancel it, update your card on file, and see charges: https://www.thetappingsolutionapp.com/premium/login.php