Hi! Is there a way to cancel a subcsription purchased via Testflight? The subscription is not displayed in Apple account's Apps & Purchases.
Cancelling a subscription
Sure, you can. The best way to do this is by using a Sandbox Apple Account. See how to create one here, and follow along with this article on how to test disabling auto-renew for the specifics on testing how to cancel a subscription: https://developer.apple.com/documentation/storekit/testing-disabling-auto-renew
The subscription expired on its own. There were 13 renewals, instead of 6. Testflight subscriptions should renew no more than 6 times, as per Testflight's documentation.