The product key is stored in the Windows 10 Registry File, so it is possible 
to find the code there if you know the right key. Type "regedit" into the 
Windows 10 desktop search and select the appropriate item in the results. 
Navigate to this key:

Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SoftwareProtectionPlatform

As you can see in Figure C, the BackupProductKeyDefault key will reveal a 
valid Windows 10 product key.