I agree with Ana. When you purchase a game, the default is that the box is checked to join. If you have missed that checkmark, you will be signed up for a free game credit every month and charged for it. Big Fish doesn't try to hide it or be sneaky. It's right there.
As dianne says, you have to carefully UNcheck it each time. No sneakiness is involved. If 299 people have simply not noticed or checked, I'm finding it hard to understand why this is a problem. I fix WAY too many computers because people don't carefully check download pages for checkmarks for "extra" junk that turns out to be malware. But then on the other side of the coin, maybe they need to have a more prominent notice in big letters and bright colors that says unless you uncheck the option, you are signing up.
Fireplace, yarn, knitting needles, books, wine... check. Yup, I'm ready for winter.