MuditaOS will be released on the GNU GPL v3 License. We decided to go for this copyleft license so that any forks and changes made to MuditaOS will have to be released on the same license (made available to the public) and documented.

Does MuditaOS with an Open Source license means anyone can use it on their own E Ink device for free?

Yes, however any changes done to the software need to be released and documented under the GPL v3 license.