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 the Apple App Store/iPhones
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.
For Google Play/Android Devices
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.