Once you have started a subscription to Know Me Plus, there is a Manage Subscription link at the bottom of the Store screen. Tap this to go directly to a screen where you can see all the subscriptions from apps you use.
If you would like to go directly through your iPhone or iPad’s Settings instead, follow these steps:
Go to the Settings app on your iPhone or iPad.
Tap your name at the top of the screen, then tap iTunes & App Store.
Tap your Apple ID at the top of the screen, then tap View Apple ID. You might need to enter your Apple ID password.
Tap Subscriptions, and choose Know Me Toolbox.
From there, you can choose a different subscription period or cancel your subscription. If you cancel, your subscription will stop at the end of the current billing cycle.
For more information, or for instructions to do this from your Mac or PC, see this page on Apple’s website.