Just downloaded NX 10.0. I have the new license file, but can't remember excatly how to replace it.I've done it before, if I wrote it down somewhere I can't remember where. I successfully replace the NX9 but I am unsure what I did. Couldn't find anything skimming through the docs either.
The NX Help files (AKA 'User Docs') includes a section titled 'System Administration' which includes instructions on setting up the licensing software and enabling your license file.
Note you do have to upgrade the license server software (not just the license file) for NX10
Production: NX10.0.3.5 MP16/TC11.2
I'd rather be e-steamed than e-diseaseled