MailStream Plus 8.3.1 and later versions, on UNIX/Linux. What are the /opt/pb ‘shared license area’ or ‘shared license file’ referred to in the MSP installation guide?

Operating System: UNIX/Linux
In the MailStream Plus (MSP) 8.3.1 and later Installation Guides, in the UNIX/Linus install instructions, it refers to shared license area’ and ‘shared license file’ in several places: 
• You must establish a shared license area in /opt/pb. During the installation process, the installation script provides these shared license area setup options:
• Install anywhere on the UNIX/Linux machine you need for production purposes: This will be the production installation area, and will be tracked by the shared license file.
• Install to a test area: The test area will not be tracked by the shared license file, so any patches/updates will not be applied to any test area. You may create as many test areas as needed.
Only one area will be tracked by the shared license file: the production area selected during the installation process.
What does that mean by ‘shared license...”?
It is just terminology for the folder.  There are no actual MSP licenses located there.  The .pitneymsn hidden file in the /opt/pb/var has a pointer to where MSP is installed, and the MSP license and the Acucobol license are located within the MSP installation area.
In the future, as new products are released, for some of them there will be other .pitneyxxx files with similar pointers.
UPDATED:  April 21, 2017