I downloaded Windows XP mode and extracted a virtual hard drive and installed it into Virtualbox as a virtual machine as per a prior Makeuseof article from April 18, 2014.
The problem is that XP Professional requires activation; you get a 30 period in which to do so. Both telephone and Internet activation are rejected. Windows XP mode was made for windows 7 but I run windows 8.1, which may be why things don’t match.
The April 18 page suggests making a snapshot of your fully set up system on day one and then just restore that snapshot later in the 30 day period.
However that does not work as the program seems to give you 30 days and any change in system date reduces that 30 days.
There is a key file in the original XP mode package but I have been unable to open it with any program.