com_directorytree is a jQuery directory tree extension customized for Joomla! It is released as a commercial extension under the GNU/GPLv3 license category: http://www.gnu.org/licenses/gpl-3.0.html. With the purchase of a single user license you have the freedom to share and change all versions of the software providing it remains under the GNU/GPLv3 license category and does not infringe any of the terms or conditions as indicated in the GNU/GPLv3 license agreement. The purchase of a single user license pays for technical support and development of the extension.