The installer should have both home and pro. You'll just have to specify which during the install. Windows 10 installers do the same thing. Also, that key should work if you want to jump to windows 10.
Ah ok. I just going to ask this because the only options I have are Windows 8.1 N and Windows 8.1 NR or some weird version like that. I've never even heard of those versions.
I download the "normal" windows 8.1 64bit.
So after I burn it and stick in my friends PC I should get an option to choose the "pro" version?
About windows 10, I don't think he wants to use windows 10. Also, as far as I know windows 10 can't be obtained for "free" anymore.