1. Apparatus for determining program usage on a computer having a plurality of storage devices, said apparatus comprising: first, second and third memory means; said first memory means storing a list of program module names of program modules and for each of said program module names storing a product name associated therewith; surveying means that surveys the storage devices and stores in said second memory means module names of modules stored on said storage devices; associating means that stores in said second memory means an association between the product names stored in said first memory means and each of said module names stored in said second memory means; monitoring means that monitors invocations of said modules on said computer system and stores in said third memory means invocation data relating to said invocations of said modules; correlating means that correlates said invocation data stored in said third memory means and said association between the product names and each of said module names stored in said second memory means; and reporting means that outputs the data correlated by said correlating means.