Quick Windows 10 install question

[Kerplunk]

Hello guys,

I am looking to upgrade my current Windows 8 system to Windows 10, I have downloaded the MediaCreationToolx64. Do I have to choose upgrade, or can I create an ISO and do a clean install? Does it matter regarding licences?

Cheers!

 

[Kerplunk]

Thanks guys! I'm on Windows 8, not 8.1 do I HAVE to upgrade to 8.1 first?