Using Old Hard Drive In A New Computer?

[Pandro]

So, I'm planning to build myself a new computer for basic stuff and a little bit of gaming. Currently, I'm using an HP desktop with Windows 10 installed. I bought this computer from a guy in Craigslist (Back in November of 2016). He said he did a fresh install of Windows 10. The computer originally had Windows 7 so I assume he took advantage of the free upgrade. Of course, I want to save myself some money by not buying a new key and hard drive. Is there a way to use my drive in a new build and have Windows 10 still installed? I have read countless of articles and forums but it's too much for my brain to process. Thanks in advance!

 

[Colif]

Do this now and after you upgrade and you can move Win 10 licence to new PC - Reactivating win 10 after new hardware