Answer
ArcIMS does not normally consume an ArcInfo license. However, if this is happening, one likely cause is the original version of an ArcIMS 4.0.1 patch.
The "ArcIMS 4.0.1 - Image Server and Custom Raster Update", released April 11, 2003, was subsequently recalled, corrected, and rereleased June 13, 2003.
If you are still using the original patch, please upgrade to the June 13, 2003, version. A link to the patch files and installation instructions is provided below.