BEdita is free and open-source software (FOSS) released under GNU Lesser General Public License v3.
"...The LGPL license allows developers and companies to use and integrate LGPL software into their own (even proprietary) software without being required by the terms of a strong copyleft license to release the source code of their own software-parts. The license requires that only the LGPL software-parts be modifiable by end-users via source code availability" (from Wikipedia)
With BEdita you can build your own proprietary or free software modules, frontends and addons without limitations, but you have to make available source code modifications of BEdita itself if you publish a modified version.