[SOLVED] I am reinstalling Windows 10, do I need serial key?

[WTFLLama]

So my notebook had Windows 8 when I bought it but I upgaded it to Windows 8.1 and then Windows 10 with official upgrade programs. Now I completely wiped the hard disk and I want to reinstall Windows. Which version do I need to install so that I don't need a serial key? (I prefer Windows 10, of course)

 

[SkyNetRising]

Install windows 10 - same edition (home or pro). Wrong edition will not activate.

 

[Colif]

When you get to screen asking for a key, click "I don't have a key" and win 10 will continue to install and reactivate once it connects to internet afterwards