Need to manage your Amazon App Subscriptions? Follow these instructions on Amazon's Help Page: https://www.amazon.com/gp/help/customer/display.html?nodeId=G57V745LBUAWDQ78
You can manage your Appstore subscriptions using one of the following methods:
On the Amazon website:
Go to Your Account, and select Apps and more under the Digital content and Devices section.
From the menu on the left, select Your Subscriptions
Fire tablets:
Tap Apps, and then tap Store.
Open the menu, and then tap Manage Subscriptions.
Amazon Appstore:
Open the Amazon Appstore app.
Tap My Apps.
Tap Subscriptions.
If you run into any issues or have questions on Amazon, please contact their support: https://www.amazon.com/gp/aw/contact-us.