it depends on how the Win7 COA key was activated
if it activates via online/internet, you're good to go. if it fails internet activation with an error, call Microsoft
and activate by phone
https://answers.microsoft.com/en-us/windows/forum/all/reinstallation-of-a-windows-7-oem-coa/0dbdc16b-6355-4c79-be91-ddd2f140248d
https://www.sevenforums.com/tutorials/18715-activate-windows-7-phone.html