Business Process Portal for WordPress is free software, released under the GNU General Public License, version 2 or later, the same licence as WordPress itself.
You may use, study, change and share the plugin under the terms of that licence. A paid licence key gives you unlimited models and updates for as long as it is active.
Read the GNU General Public License
The diagram editor is built on bpmn-js from bpmn.io. [THIRD-PARTY LICENCE NOTICES TO BE LISTED HERE.]