You must cancel the subscription yourself from the App Store or Google Play Store.
Uninstalling the app does not cancel TimeTree Premium.
Please cancel at least 24 hours prior to the expiration of your subscription plan, before the subscription will automatically renew
How to Cancel
iOS
Open the "App Store" application
Tap the person icon in the upper right corner of the screen
Tap "Subscription" on the "Account" screen
Tap "Cancel Registration" on the "TimeTree Premium" you purchased to cancel your subscription. *Make sure you are signed in with the Apple ID you used to register for TimeTree Premium
How to confirm cancellation:
If the subscription you are using is "Scheduled to End", your subscription has been canceled.