If you start a commercial edition or trial edition of PRTG Traffic Grapher it will shortly check your network if there is another installation running with the same License Key.

If this is the case PRTG can not be started and you will see the message:

Multiple Instances Detected - Sorry, but you can only run one copy of PRTG Traffic Monitor in your network with your current license!

You are not allowed to run a license of PRTG Traffic Grapher on more than one machine in your network at the same time - except if you have purchased a Site License.

If you get the message above but don't know what other machine runs the same key, open a command line session and use the following commands to find out what other machine is in your way:

cd "c:/program files/prtg traffic grapher"

"prtg traffic grapher.exe" SHOWNETUSERS

Note: If you did not install into the default folder please use your installation folder in the first command!

After a few seconds you will see a dialog box that will show all the machine names that run the same license key as your local installation. If PRTG is currently running on your machine its name will also show up on the list.