Tendenci is an open source content management system built for non-profits, associations and cause-based sites. Functionality including association management, event registration, membership management, forums, photo galleries, donations, payments, newsletters, CRM, and much more.
https://demo.tendenci.com/ - resets every hour or two. Use "admin/admin" or "user/user" to login and look around.
Please see install documents located at:
"Connect and Organize the World's People"
The License information (GNU GPL) can be found at https://github.com/tendenci/tendenci/blob/master/LICENSE.md