If you purchased a subscription on an iOS device, you will need to contact iTunes Support as it falls under iTunes Terms of Service. Refunds can be issued by iTunes Support team only.
The official App Store and iTunes Store policy state that all sales are final, though there are a few exceptions. You can get a refund for accidental purchases if the app does not work as described, if you are charged but do not receive the item or if the app is not compatible with your device.
If you purchased a subscription on Google Play, you can get a refund if your purchase is not what you expected, if there is a problem with your purchase or if you purchased it by accident. Contact us at firstname.lastname@example.org, send us a proof of purchase or tell us which email address is linked to your Google Account, and we'll get back to you shortly!