First, yes you would definitely need to have the software on every computer and be licensed for every system that you run Terragen on. That being said, each license of Terragen 2 comes with at least 3 and as many as 5 additional render nodes (3 for versions without Animation). So you may already have all the licenses you need.
You can use Crop Rendering to split up single, high resolution renders across multiple systems, however it would take time to setup each image for multiple crop renders as it must be done manually (one could, however, easily script changes to the human-readable XML format that Terragen uses to save scene descriptions, .TGD format). For this reason rendering animations across multiple machines is the most common and practical approach. Single images are often not worth the overhead in setup time to render on more than 1 system, unless the resolution is very high. You would also need to have some easy way of reassembling the split-up sections of the image. There are image stitching programs that can do this for you automatically, some are even free.
To manage rendering, you would probably want to use a render managing application. We have a list of software that specifically supports Terragen 2 here:
http://planetside.co.uk/index.php?option=com_content&view=article&id=18&Itemid=158 (scroll down to "render managers")
I don't know if any of those support automatic setup for crop renders split across mulitple machines, so it may be somewhat laborious in practice to actually do this.
- Oshyan
