Volume license disks will do as you say. You need the PID but don't need to activate the OS. If the OS is now asking you to activate it, have you tried to do so. A last resort, if you've got a legal copy of Windows that's not accepting the code or activating properly is a call to MS to explain your problem.
how can i reactivate a copy of window 7 ultimate which, when activated for the first time did not need to insert the activation code/producct key.

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