Oomlaht

How do I determine whether I have the multi-device version? Is there an upgrade option?

I have Fences 5. I've read in a number of places, including this forum, that I can install it on up to 5 computers. I cannot. When I look at my account info for Fences 5, I have one PC listed that is already using Fences 5, as expected. It appears that I am limited to just one activation. Please clarify.