My first guess is no.. It does some checks to see if the disk is in the array. That might break.. But that's just a guess...
Someone else may have a better, more accurate, answer.
I've done a spare usb drive with unraid eval before on another machine..
Boot to usb.
Run unraid.
Go back to normal os.
Might be a little more complicated now that you have to get a temp key from limetech.
Jim