Installing a new OS is a hassle in it’s own right. Switching an OEM key on an already deployed OS is a nightmare. No amount of wiping the hard drive is going to allow you to switch the product key. After reloading a computer with an OEM OS several times, I figured it out. In order to change to an OEM product key, you have to create two additional files for your Windows 10 live media. The following files can be created using Notepad which Windows will then automatically load and use when it installs the new operating system.
This configuration file tell windows what edition needs to be installed. If you are trying to move from Home edition to Professional, you need to indicate Professional in this configuration file. For example, your configuration file needs to look like the following:
[EditionID] Professional [Channel] OEM [VL] 0
[EditionID] indicates the version of Windows that you would like to use. [Channel] must be either OEM or Retail. In our example, we are using an OEM key. Finally [VL] stands for volume licensing. If it is a volume license, this should be set to 1. Otherwise, change it to 0. Save this file with the file extension of “.cfg”
This is where the produc key is typed. It must be typed in the following format:
Save it as a “.txt” file.
Saving to Image
Open your Windows 10 media and copy both of these files to \Sources. Both must be present. If you omit the el.cfg, it will not for just the new product key. Boot to your modified live media and you should be see the installation for the version of Windows you indicated in the el.cfg file. If it doesn’t load properly, ensure that your product key matches the version of Windows that you indicated in your el.cfg file.
For more information, refer to Microsoft’s guide found here: https://docs.microsoft.com/en-us/windows-hardware/manufacture/desktop/windows-setup-edition-configuration-and-product-id-files–eicfg-and-pidtxt