If you are replacing an old computer with a new one, you might not need to buy a new key. Your ability to transfer a license depends on its "channel":
The short answer is , you generally need a separate license for each computer you want to keep running Windows 10 simultaneously . While you can use the same installation media (like a USB drive) to put Windows on multiple PCs, Microsoft's licensing rule is "one license per device". do i have to buy windows 10 for each computer
However, whether you have to pay for a brand-new license depends on what you plan to do with your old computer and what type of license you already own. 1. Can I Transfer My Current License? If you are replacing an old computer with