So, yeah. I upgraded from 7 to 8 on that $39.99 promo special, so I have a legit 8 Pro key. Is there any way to use the Pro RTM 8.1 ISO to upgrade or clean install 8.1 and be able to activate? To complicate matters, I've gone through 3 motherboards and used the same key on all 3 so I've had to call Microsoft actually twice to phone activate (automated method). Sorry if this has been answered already, I looked around for awhile and couldn't find anything regarding the promo upgrade key.