even that does nothing useful, as a fake server can be set up.
you need irreplaceable functions to be running on a server, functions that go to the core of the enjoyment of the game and which cannot be easily reverse engineered to make a simulated version of the server.
unfortunately the more you put on the server the higher your ongoing operation cost is going to be and the more outraged your players will be when you shut down servers and the game stops working, so such a technique will only work for one or two release cycles before word gets out that buying your games is a waste of money.