Make cancellation easy. Seriously, don’t make it difficult in the least. The worst thing you can possibly do is make someone call to cancel their subscription. It may yield you an extra month of their subscription money since people are generally lazy, but it will leave such a horrible taste in their mouth that they will NEVER come back. Ever. Feel free to ask for brief (key word #1), voluntary (key word #2) feedback, maybe a series of check boxes that they can select for why they quit. But, make it a simple, easy to understand, quick, painless process. If you do, the player will be infinitely more likely to come back if and when they get the itch.