I've been able to replicate this behavior on three different PCs, but support is having no luck getting it to occur, so I thought I'd take it to the forums and see if anyone else can.
When I'm connected to the Internet, Stardock Central behaves exactly as expected.
But I've noticed that when my PCs are not connected to the Internet (either when the ethernet cable is unplugged or I have disabled the NIC), all items under Galciv2 in SDC (tutorials, movies, multimedia, DA) say "Purchase" in the Action column. This is not the case if the PC is on-line. The game still does run, however (as long as I try to run it from the Start menu), so it is properly activated.
Interestingly enough, the "Purchase" button also shows up under my original Galactic Civilizations (GalCiv1) folder in SDC: next to the "Multimedia" and "PDF Manual" entries. Again, this only happens when not connected to the Internet.
Of particular note is that the "Purchase" button DOES NOT show up for the "root level" applications themselves of GalCiv1, AP, and GalCiv2. So this appears to be an unusual bug in SDC, that perhaps occurs with any/all subentries that are in the subtree underneath the "plus" sign from a main application entry.
-HM