Those of you who paid Microsoft a license to legitimately have Windows, they know what a product key means.
If you ever want to move Windows to a new computer and you don't plan to use it old, you don't need to pay another one operating system.
If your license is not OEM but Retail you can enable the old copy of Windows on your new computer.
The simplest way to activate Windows 10 is to sign in to your Microsoft account. In case you don't know, your Windows license is tied to your account with the company. To validate the product key, the operating system sends some information on Microsoft servers. This data is unique to your computer, (processor and motherboard information). So if you change hardware in your computer, i.e. a new CPU or motherboard, the Windows you are running will probably be disabled.
So if you can't activate your operating system by logging in to your company account, you'll need to use the Windows 10 product key. Some computers (OEMs) probably have the key on a sticker. If it is indistinguishable there is ShowKeyPlus.
ShowKeyPlus is a free tool that finds your Windows product key. Run the program and it will show you the operating system name, product ID, version and key. It also shows you if your license is OEM.
Click save and ShowKeyPlus will save the license data in a text file. You may find this information useful in the future.
Download the application from the Microsoft Store