http://www.gnu.org/licenses/gpl-2.0.html

After purchasing access to download this plugin you may download it as many times as you need to for a period of one year. By downloading and installing this plugin you agree to the legal terms allowing you to install this on one domain. If you plan on installing this on several domains please purchase additional domain approvals. You can change the coding to configure it against your registered website domain. You cannot repackage and sell, or distribute.