Activating windows 7 with phone activation code

[nicky00]

I bought a genuine copy of windows 7 professional some time ago and used a phone activation code to activate it on a pc originally. As it is no longer supported, I cant activate the installation online or by phone and was hoping to be able to find the activation code in the system and reuse it if I need to re-install the os again. Any ideas would be appeciated.