Although this question seems to be out of the scope of this forum, I think I can answer it. Basically, it comes down to having a license for each device to have Windows installed. If you are using the same key for all, then you need an Enterprise agreement with Microsoft which entitles you to a Multiple Activation Key. Otherwise, a retail key will only activate on only one computer and will fail on the rest, which means you will need different keys for each computer.
is it illegal if i create a fresh custom image and install to many laptops with same model, same unit, same drivers same specs with embedded product key to each unit?
creating image