Features like this really do require a subscription model. This isn’t enabling remote start by pressing a key on your fob. This is sending a request to a server, which connects to a cell tower to broadcast signal saying “turn on this car”. That stuff ain’t free. Someone has to pay AT&T for the data connection.
What BMW was (is?) doing is abhorrent. You’re buying a car with heated seats, and you have to subscribe to hit the button.