Moonenvy :
DSzymborski :
http://www.zdnet.com/article/microsoft-tweaks-activation-rules-for-the-windows-10-anniversary-update/
And no it's definitely not recommended that you simply move a hard drive over to a new build. Operating systems are not Lego; sometimes it'll work, sometimes it'll be unstable, sometimes it won't work at all.
Also, if you're worried about losing data, having your data on one drive rather than having a real backup solution is essentially a guarantee that sooner or later, you will lose your data.
I dont see why it wouldnt work wouldnt the pc just recognize it as a hard drive then use it to run off of.
No, it doesn't work like this. Again, PC installs are not Lego and your Windows installation is geared towards working with the specific hardware that's installed, from the various motherboard components to your GPU. The farther your new hardware is from your old hardware, the more likely it is it will be extremely unstable or simply not work at all.
What exactly do you think happens during the installation process of Windows? Nobody will recommend you do this because it's irresponsible advice. Anything worth doing is worth doing correctly.