Have a read of the top story on this page if you used your credit card to purchase ZA, McAfee, Windows Live OneCare or Symantec.
Thats one of the reasons its always better to buy a boxed copy from a store. Of course you could avoid having to worry about subscriptions all together and pick the free stuff.
Similar to what they do with car insurance now, ie they renew it automatically 'to save you the hassle' (not to keep you with them of course).
I just had a letter from my insurance company to tell me they would be automatically renewing my car insurance, despite the fact the car doesn't even exist anymore. It was stolen a couple of months ago, written off and scrapped!