Short answer
Turn auto-renew off in the app before the next billing date if you do not want the plan to renew automatically.
Steps
Open the app.
Open Settings.
Tap Manage Subscription.
Turn auto-renew off / cancel the subscription.
What happens next
Your current paid period usually stays active until the end date. The next renewal should not be charged.
Important
Turning off auto-renew does not automatically refund the current billing period.