I found my answer!
I found the answer in the Support > Frequently Asked Questions section of AppThemes.com It reads the following:
What license does AppThemes abide by?
All our themes are licensed under the GNU general public license which means they may be used by our customers on as many websites as they like. Customers purchasing the Professional Edition have access to the Photoshop design files. These source files are licensed and copyrighted under AppThemes and are not GPL. You may not redistribute these files or claim them as your work.