Once you activate a free trial through the Google Play store, you will need to cancel at least 24 hours before the trial ends to avoid being charged for the annual subscription.
Remember - you will need to cancel through the Google Play store settings on your device.
1. Open the Google Play store app.
2. Press the menu button in the top left corner of the Google Play store app (3 horizontal lines)
3. In the side menu that appears, press Subscriptions.
4. Press the Pray.com free trial subscription.
If you do not see Pray.com, this means you do not have a free trial on this Google Play account.
5. Press 'Cancel subscription' and confirm cancellation.
If you run into any trouble, this Google Play help article includes additional details for cancelling your free trial.