On my machine (so i gues in general).
The licence is kept in place.
So when u have bought the standard version and a newer C2 version becomes available.
U just download and install it.
Even when it prompts that the installer needs to remove the previous version first, u just click ok and let it do its thing.
All your pluggins behaviours and licence are kept in place and construct 2 automaticly knows where they are.
C2 is made by some clever people.