Habari is released under the Apache Software License. The ASL makes no restrictions for released works. In fact, it specifically says that the ASL does not apply to works that merely link to the original:
Derivative Works shall not include works that remain separable from, or merely link (or bind by name) to the interfaces of, the Work and Derivative Works thereof.
The ASL seeks to apply a license that protects the original work and allows a vibrant ecosystem of both free and commercial interests to take part. Just as free and open alternatives to pretty much any commercial software you can think of have arisen over the years, the ASL will allow the same behavior to build a thriving community for Habari users.
People have asked countless times why Habari doesn't use the GNU General Public License. It limits what libraries we can include because including GPL code in Habari's core code would taint Habari and require that we release it under the GPL.
Applying a license to your software that removes the freedom of developers to license their ancillary software (themes and plugins) as they see fit doesn't seem right to us.
We want our themers to have the right to charge for their hard work. We want a rich ecosystem of themes and plugins where market competition - not measured simply in money charged, but in who can make the best modules, free or not - dictates the flow of interest.
If this sounds like the way you think things should be, welcome to Habari, we think you'll love it here.