How do I get my money back from a subscription

You may cancel a subscription to an app --> See or cancel your subscriptions - Apple Support

You can also request a refund for a recent renewal of an in-app subscription purchase 

If you have purchased an app there is no way of getting the refund. However, you may try -->  Request a refund for an App Store or  iTunes Store purchase

At times subscription refund may not be possible, however you may change or cancel a subscription—or check if a charge from Apple that you don't recognize is for a subscription—tap or click this button: