Subscriptions on Google Play renew automatically. If you wish to unsubscribe to a certain app/promo, you can cancel it on Google Play.
Make sure to check the official page Cancel, pause, or change a subscription on Google Play to have more information, a step by step guide and direct support from Google.
Please bear in mind that if you do not unsubscribe at least 24 hours before the expiry of a subscription period, you will be charged the subscription price for the next subscription period.
In order to access the Subscription settings:
1. Access the Google Play store and tap on the Menu Make sure you are logged-in in the correct Google account where you set up your subscription.
2. In the Subscriptions tab, you'll find the subscriptions you currently have and will be able to cancel any of them, as you wish. Just tap Cancel subscription and follow the onscreen instructions.
We hope this helps!
Please also check: How to cancel weekly/monthly Subscriptions - iOS