Manually setting the path in settings.dat to the program directory fixed the problem - I hope not just temporarily...
So, yes, there is a bug.
Help-->License Information-->Install new license does not work. After using this function, the program fails to reopen and the settings.dat file continues to point to the desktop. It does not rewrite the settings.dat file.
If the license file is installed from, or autodetected on, the desktop, the program continues to open as it should -- provided that the license.xbin file remains on the desktop.
If the license is installed from anyplace other than the desktop, the program either opens once, and then reverts to trial mode, or goes directly to trial mode. I can't establish a pattern for the once|never condition.