I am sure this has been answered earlier but I can't find the answer. 

I have bought a new ssd and am planning to install it in my Laptop. The existing HDD has a very high capacity but has gone very slow. Is it possible to activate windows 8.1 in my SSD. If so is it possible for me to keep both activation. I am planning to use SSD for daily use and my HDD to use when in need. Both the installations will be used in the same PC. Or if I activate windows 8.1 in my SSD would I have have to stop using HDD boot if it violates licence. I know the HDD can be used as an external drive but I would prefer to keep windows in it as I have lots of other software installed.

It is only one installation per licence. Once you install to the SSD, you can no longer use the other Windows on the hard drive.

Hi Mexicanking,

"If so is it possible for me to keep both activation."

I am afraid it is not possible to keep both the system activated .Just as Lead3 said ,we can only keep one installation .

We can refer to the following link to replace the hard drive (In Windows 8.1 ,we create a recovery drive and system image ):

Restoring your PC after a hard drive failure

http://windows.microsoft.com/en-HK/windows7/help/videos/restoring-your-pc-after-a-hard-drive-failure#tab=system

Best regards