The suggested way of retrieving serial number of LabVIEW is only applicable to LabVIEW. You will not able to retrieve the serial number of other NI software, e.g. TestStand, in the similar way.
Per NI Software Policies
and NI General Purpose Software License Agreement
, for Single-Seat user, you are allowed to retrieve the serial number and use it to activate LabVIEW on another computer.