Refund process depends on where and when you purchased your subscription. Both Google Play and the Apple App Store have different policies when it comes to issuing a refund.
Google Play Store: Refund policies are different depending on what you bought.
You may get an automatic refund if you uninstall a paid app shortly after first buying it. If you want to reinstall the app, you'll have to buy it again and you will not be eligible for a refund on that purchase.
Note: If you give your account or payment details to someone else, appear to be abusing our policies, or don’t protect your account with authentication, we usually can’t issue a refund.
We are usually able to accommodate refund requests made within 30 days of your purchase. Please reach out to us at email@example.com or head over to our Support for assistance. You can send us your order ID number and we will check if you are eligible for a full refund via Google Play Store. For more information head over to https://support.google.com/googleplay/answer/2479637?hl=en
iTunes App Store: Apple handles all billing for in-app purchases. Customers subscribed through iTunes will need to reach out to them directly with any refund requests.
They are typically able to honor all refund requests within 30 days of the purchase date (but it's at their discretion). You can contact iTunes Customer Support directly at https://getsupport.apple.com/.