There are only three reasons why it would deactivate.
1. Deactivated from Go Pro page.
2. Deactivated from wpfront.com purchase history.
3. Site home URL changed.
Is there any chance that one of these would have happened? How many times did this happen? Did you check your purchase history before activating again to see whether that site exists within the list?
I understand that how this will be an issue from a security stand point. I’ll add email notification with grace period and audit trails in next version so that you will be notified on accidental deactivation with enough time to reactivate. Nothing changed in v2.10 on licensing functions, so I doubt it.