I could imagine a future TV requires phoning home every 30 days or else it stops functioning. Single network source for both the "license" check + the ad network so as to simple deny rules.

Yes, of course it will have a grace period (of similar length to the store return period) before it starts up. This will all be buried in the EULA you didn't read.

I would bet “similar length + 7 days” so you won’t know about the requirement until after you can’t return it.