It is registering the license to you (the user). You "activate" the application on a PC. That is why you can deactivate the application from a PC and install and activate it on another PC without affecting the registration of the product.
Read the RoboColum(n).
Hmmm...We purchased 14 user licenses. If I wanted to remove a license from one user and give it to someone else, how would I do that? And are users tracked by the name that was entered during registration?
As Colum said, you deactivate it on one PC and activate it on another. You don't have to uninstall it on the first one if you think you might want to transfer the licence back. You could deactivate it on the second PC and reactivate it on the first.
You have effectively bought the right to have it activated at the same time on 14 PCs.
See www.grainge.org for RoboHelp and Authoring tips