The latest stable release can always be downloaded at SourceForge:
Download (SourceForge)
Click release names for more information.
The Mobile-App has no release cycle like d3web KnowWE, but we will provide versions compatible with the current d3web KnowWE release. While d3web KnowWE is platform independent, the Mobile-App is not. So sure to use the correct download.
The releases linked on this page are licensed under LGPL.
For optional commercial extensions, please contact denkbares.
Further information regarding licencing: FAQ: Licensing