If you do not have this, do not install it. If you have it and it is working NEVER UPGRADE!
The author has removed functionality from every upgrade to try to sell the Pro version, so people with substantial ad databases have been his beta testers without their knowledge. Actually, there is a lot of stuff here that you won't use if you are a small blogger which could be basis of a commercial version, but the basic stuff is being removed too. So if you are a small guy with many ads you are SOL.
If you have a small database, consider replacing this now. If you have a large database, back it up and back up your working version of the plugin in case you accidentally upgrade or have to adapt to WP changes.