Well not sure about premium but I had activation issues and i did the following
1: clean install of windows7
2: try to activate (no joy)
3: ran the following
net stop slsvc
Ren tokens.dat tokens.old
net start slsvc
4: rebooted and try activation (again no joy)
5: run windows 7 upgrade from disk
6: tried to activate received wrong serial requires ultimate product key????
I have windows 7 pro... On checking it seems yes my pro is now ultimate and has stopped asking for activation and states it is indeed activated???
no idea how this happened but I am now happy with my new windows 7 OS