You may cancel your subscription at any time. However, there are no refunds for cancellation. If you cancel before the end of your billing cycle you will have access to your account for the remainder of the billing cycle.
To cancel your account:
Navigate to your Account page while logged into FutureFlight.aero.
Click on the "Cancel Subscription" button under the "Subscription" section.
"Confirm" your cancellation on the following page.