And if I had to sign off the internet chances are I wouldnt be able to do what I wanted to do anyway?
I leave steam on at my friends while I download a game. I come home, switch on my home pc, it tells me I'm signed on at another place and signing on here will sign me off there. Incidentally, even when that happens it still keeps downloading my game at my friends house.
There are plenty of ways an acceptable medium can be found, Microsoft just isn't interested. There will of course be plenty of people who pay for windows on multiple pc's, same as there will be people who refuse to pay for it multiple times and those who just pirate windows instead.