If you use Xfrog to build trees, plants, ground cover, etc. you must create, from scratch, the geometry and all associated textures. You may not distribute any models created by Greenworks. These are the ready made trees, plants etc. that ship with or are purchased separately for Xfrog. You may use their models in your personal renderings just don't give them to other people.
The trees, plants etc. that you create (in Xfrog) from the ground up, using your geometry and textures, may be sold or given away.
Walli, in my opinion, is the last word on this since he works for or contributes to Greenworks.
This is my understanding also, this topic is getting tiresome.
Marc
If a bus station is where a bus stops, and a train station is where a train stops, then what happens at a workstation?
Where the work stops."The first thing we do, let's kill all the lawyers" - Shakespeare