The activation is not computer linked and internet is only needed for 3D, The serial number needs to be activated on airnav servers. I have radarbox installed on 2 computers - 1 desktop, 1 laptop and never needed to activate (no activate button within the software anyway). Just install, enter the username and password, thats it.
I also installed it on my friends laptop (Windows 7) to demonstrate the radarbox (he wanted to see before he buys one) and it worked without us being on the internet, I don't subscribe to 3D.