vcenter 5.0 on windows server 2008 r2 license became 'not genuine'

chronology of what had been done prior this issue

1. create a new vm
2. copy and paste vmdk file of a vcenter 5.0 (windows 2008 r2)
3. power on vm
4. set IP same as original vcenter
5. successfully activate windows licens
6. migrate vcenter to another esxi server

what would suddenly cause this?