Esri License Info.
Use the ESRILicenseInfo object to determine the current license level in use and whether a specific product is licensed.
Windows, Solaris, Linux
|IESRILicenseInfo||Provides access to members that check software licenses.|
The object models for ArcView, ArcEditor, and ArcInfo at ArcGIS 8.1 are identical. All classes, interfaces, methods, and properties are present in all products. This means that the same DLLs containing the same components with the same GUIDs are installed for all deployments; in other words, code written on one deployment will successfully compile on another. What will differ for the various deployments is the behavior of certain method calls.
As a developer you may need to know what license is currently checked out by the user, so that your code can be robust enough to work on all deploymets, or at least have the appropriate error checking.
To determine the level of license currently in use, use the ESRILicenseInfococlass and the DefaultProduct property on its IESRILicenseInfointerface.