How about, at the very point one sets up their app to use your service, they provide a secondary api endpoint of their choice (licserver.customerdomain.com). Th

How about, at the very point one sets up their app to use your service, they provide a secondary api endpoint of their choice (licserver.customerdomain.com). That way if your server goes belly up, it falls back to their domain for license management without the user have to update their software because the vendor needs to point to a new service.