not so long ago PTC used to supply node locked licenses (the third
licensing option which says "license file"). If you had one of these
you could start multiple sessions of Pro/E on a single machine with a
single license provided you had enough memory so they didn't
excessively page. From what I recall, you didn't even have to have flexlm
running with this option but don't quote me on that.
This functionality was really useful if you were doing a very
complicated reroute due to loss of grandparent features. You could open
up the "before" model in one session and the "after" model in the other
session so you better see where failed features were referenced to.
It was even possible to have several versions of Pro/E running concurrently.
I think PTC stopped dishing out node locked licenses because some users
were starting up several crunchy sessions of NC machinist on one
machine so that could start on the next one before finishing the