No, you don't need to reenter the product key after Reset.
No, you don't need to reenter the product key after Reset.
The laptop might be saved in the BIOS even without a license, so it’s worth checking there if necessary. After setting up Windows 10 via CMD, running the command should display the key. If you haven’t reset it yet, try this before proceeding. This method only works if the BIOS is active, but it could be useful in your situation.
The laptop comes pre-installed with Windows 10 Pro, or your friend could have linked the key to a Microsoft account by accessing Windows through one. You don’t have to re-enter the key. Just wipe the boot drive, then install Windows 10 Pro without a key, and activate it by returning to the Microsoft account used before. Go to Settings > Update & Security > Activation.