I have recently decided to upgrade my laptop to an SSD. This has meant that I will need to reinstall Windows 8.1 Pro from scratch. I had first got Windows 8 from Dreamspark last year as an ISO download, and a key (which was only on their site, besides, they no longer have Windows 8 on there), but I kept a copy of the ISO I downloaded then (but no the key). So I have written that to a USB, and it boots up, but the only Key I have is the one I recovered from my previous installation (via Jelly Bean Keyfinder), but it maintains that it is invalid.
Is there anywhere where I can download, or somehow, armed only with a valid Windows 8.1 Pro Key, get Windows installed on my new drive?
p.s. I do have a connector so I could access both drives at the same time (boot from the hdd, and connect the ssd via usb), then copy one to the other (theres enough space), but ideally, I want to do an absolute clean