bigben - thanks for the reply. Unfortunately, this leaves too much to interpretation.
I found this post from 2009:
http://www.planetside.co.uk/forums/index.php?topic=6855.0 and this statement from a Planetside staff member (Matt) - "Almost correct, but not quite. "1 user license" means that only 1 person can be using Terragen at any one time. If you need to work on a different computer, you can, because you are still only one user using the software at any one time. It doesn't matter what computer you work on.
Quote
Each Licensed Copy may only be running on one "Machine" and operated by no more than one person at any one time, regardless of platform.
Also, whenever you are not using the software, someone else can. If you have bought one user license, then a friend, family member or colleague can use Terragen on your computer whenever you are not. As long as only one person uses Terragen at any one time."
As this post is 8 years old, it would be helpful to hear from someone with Planetside. In fact, I'm surprised I haven't by now. If I am not allowed to take a project home with me over the weekend to resume work, I don't think this software is for me.
Thanks again for the reply.