Our program has a piracy problem, some people buy a personal license and install it on all the computers in a company. We want to check that only a single instance of a serial id is used at the same time (or at most, two or three instances, say on a user's laptop and desktop).
We're thinking about having the program call home with a non traceable identifier and the license so long as the program is running (every 15 minutes or some medium length interval like this) and when we see that too many instances are running with the same serial id (let's say the average user has 3 computers max), the next time one of the instances pings us we'll send him back a response to shut down the program and display the message.
We are aware of the fact that the system can be bypassed, we are OK with that, just don't want legitimate users to use the same serial multiple times.
Are there any ethical issues with having the program call about home twice an hour? Would this have a negative impact on how people perceive our software?