Anti virus software.
I bought a McAfee one from Argos a month ago, it cost just over a tenner.
Part of the Ts&Cs was signing up to auto-renew. It didn't say how much so I did a bit of digging. Wasn't easy to find but eventually I found it was over £120!
I've jumped the hoops finding the auto renew on their website and no surprise I've turned it off. They asked why, "because the auto renewal price is bloody ridiculous!"