PRS Subscription Licensing works like this: each different PC that logs on during the day consumes a license for that day. If you logged on to your old PC earlier in the day it will have consumed a license which is not available for use by the new machine.
There are a number of ways to get round this:
|•||Wait till tomorrow — the license pool is reset at the start of each day.|
|•||Go back to your old PC just for today, start using your new PC tomorrow.|
|•||Take your old PC off the network (or rename it) then rename your new PC with the same name as the old one.|
See also the PRS Licensing web page http://prshq.com/licensing.html.