Below are instructions on how to cancel your subscription on the App Store and Google Play. The respective app stores decide if they'll issue a refund.
For Apple App Store/iPhones
To see your subscriptions
Open the Settings app.
Tap your name, then tap Subscriptions.*
Tap the subscription that you want to manage. Don't see the subscription that you're looking for?
Choose a different subscription option, or tap Cancel Subscription. If you don’t see Cancel Subscription, the subscription is already canceled and won't renew.
* If you don't see "Subscriptions" in the Settings app, tap "iTunes & App Store" instead. Tap your Apple ID (which is usually your email address), then tap View Apple ID. Sign in, scroll down to Subscriptions, then tap Subscriptions.
To see all of the App's charges
To see all of the charges for the app you can visit apple's web page https://reportaproblem.apple.com. Here you can see all the charges and request a refund.
For Google Play/Android Devices
To see your subscriptions
To quickly open the subscriptions section of the Google Play store visit play.google.com/store/account/subscriptions.
To get there manually open the Google Play app tap your profile picture in the top right, then tap Payments & subscriptions, and finally tap Subscriptions.
Under the “Subscriptions” section, find the subscription you would like to cancel. Next to it, select Cancel subscription.
Follow the on-screen instructions to finish canceling your subscription.
To see all of the App's charges
To quickly open the play.google.com/store/account/orderhistory
To get there manually open the Google Play app tap your profile picture in the top right, then tap Payments & subscriptions, and finally tap Budget & history.
Here you can see all the charges and request a refund.