QueueExplorer 4.x can load license directly from program itself, and don't have to be manually copied like before.
In order to activate your copy you should save license file (QueueExplorer.license) to folder where QueueExplorer is installed. By default it's installed here:
c:\Program Files (x86)\QueueExplorer\
c:\Program Files (x86)\QueueExplorer Professional\
c:\Program Files\QueueExplorer Professional\
If everything is ok, once you start QueueExplorer and click Help/About you should see your registration name there.
If you get an error message when accessing remote queue, please read:
QueueExplorer uses standard MSMQ API calls to perform its functionality. Most limitations come from that fact. Read more.