Free Trials of Apps. 

Subscribing to a free trial for an Android app gives you access to the subscription benefits for that app for a duration specified by the application developer. At the end of the trial period, you will be charged the price of the subscription and will continue to be charged until you cancel your subscription. To avoid any charges, you must cancel before the end of the trial period. Once you cancel your trial, you will immediately lose access to any subscription privileges.