MacOSX 10.12.5
The geometry import dialog reverts to (random) units, mostly meters or inches. If I choos mm's it should stay for next import.
KeyShot 7.0.438
+1 on this, happening on Windows 7 64, KS7 as well.
It used to remember the last setting used, especially in the same file. Have to choose the units each time I import into the same file.
Perhaps you could set the unit in the startup.bip and save this template.
This should help.