It applies to windows 8 as well. Usually you can install the same license on 2 computers in your home and with a call I believe a third. They assume you are buying one license to use on your desktop and laptop.
Again, I have been out of the industry for a few years, but this was not the case previously, and I doubt it is now. With the exception of VL, or Office Student and Teacher, M$ never sold
one license to be installed on more than one computer. The activation would work, but that does not mean they allowed you to have more than one instance of the installation. IMO, they just felt people may have legitimate reasons to reinstall a couple of times. To save themselves the few pennies it would take to force you to call and get a manual approval, they hard-coded the activation system to allow up to three activations. But, again, their assumption was (and still is) that you only have it installed on ONE device.