If the license input window does not pop up when you start ShipWeight the first time, the reason is most likely that the CMInstall software did not initialize during the installation.  To fix this, go to the folder of the ShipWeight executable on the client machine (most often in C:\Program Files (x86)\ShipWeight), find the CMInstall.exe file and run this file as an Administrator (right-click the file and select "Run as administrator")