fivebythree, we've been unable to reproduce your problem here. Please try the most recent build; the license management code is being tweaked with each release, so this may address your problem.
If not, can you give us any more details about exactly what triggers the problem?
Please check your installed Octane and plugin versions carefully. Because of the ongoing changes to the license controls, if you have more than one Otoy product installed (e.g. Octane standalone and the Sketchup plugin, or two different plugins, or any similar combination), you should make sure that all installed Octane 3.x products are exactly the same version.