We originally built Traffic Travis for our own in-house use, and later we released it as a free bonus for subscribers to Affilorama. With Affilorama becoming free, we thought it would be nice to open up Traffic Travis to the general public as well.
Catch? There is a small catch. The free version of Traffic Travis is slightly restricted in terms of how many projects you can have, and in a few other ways. We are sure that this will be of no concern whatsoever to regular users of Traffic Travis, who might just have one or two sites or campaigns they want to monitor.
The Professional version of Traffic Travis v4 is completely unrestricted, and we recommend that for people with more websites and larger PPC campaigns. And also for people who want to contribute to keeping us clothed and fed. :)