We are sorry to see you go! You must cancel your subscription on the platform on which you purchased it.
If you purchased it on the Google Play Store, you can cancel your Premium subscription by going to the Google Play Store app on your device → Any.do page, and cancel your subscription.
On the web, you can cancel your subscription by logging onto the web app and click on the left for menu → Account Status (Profile) → Manage Subscription → Leave Premium.
On Mac or iOS, you can cancel your subscription by following the directions here: http://support.apple.com/en-il/HT202039.
Note that you will still be able to enjoy premium features until the original subscription expires (the day the next payment should be made), but you won't be charged.
Users with Business subscriptions cannot cancel this way; please refer to these directions.