Here is a question that I keep seeing as more and more are updating to 9.1 ArcGIS.
When I move to 9.1 from 9.0, do I need a new license since some extensions are included for free or do the extension just activate when you are using the appropriate level of software?
If you are using concurrent copy licenses (license manger with hardware key) then you do not need new keycode files for 9.1. The changes in the included extensions are incorporated in the software and do not require a new keycode file.
Users using software requiring authorization files (ArcView & ArcEditor Single Use, ArcSDE, ArcIMS, ArcGIS Server, ArcGIS Engine Dev Kit, and ArcGIS Engine Runtime) do need to reregister their software at 9.1 using the new registration numbers provided with the update.