You can tell what version of Operations Manager 2005 you have by going into the registry and looking under
HKLM\Microsoft\Microsoft Operations Manager\2.0\Setup\InstalledServerSKU.
It will say "Eval" for the evaluation version, "Select" or "Retail" for the licensed versions.
You can tell when Operations Manager 2005 Eval version is going to expire by going into the registry and looking under
HKLM\Microsoft\Microsoft Operations Manager\2.0\Setup\InstalledOn
Add 120 days to the install date and you will know when the eval license will expire. This is unfortunately something we did not show anywhere in the MOM 2005 UI. While this is one way to find out, Microsoft does not support or recommend any customers going into the system registry.
Note: Changing the install date in the registry does not extend the Eval period either.
Information/workarounds/solutions provided may not be supported by the Microsoft Operations Manager team. Comments expressed by the blogger maybe subjective and are subject to change.