Building A New Gaming PC, Confused With OS

[Bobangkick]

So I currently have a gaming PC that I am looking to sell soon. In its place I am going to build a new PC, however I am confused about what to do in terms of the OS. On my current PC I did have Windows 8.1 but upgraded to Windows 10, is there a way that I could for example, contact Microsoft and get another copy of Windows 10 for my new PC or would I have to buy another copy?

 

[aces19]

You would have to just buy another copy. You can't "reuse" copies of windows.