Controlling access to functionality within an installed software product. The invention includes an authorization module that dynamically references authorization information when specific functionality is requested by a requesting entity such as a user or an application program to determine if the requested functionality is authorized to be executed. Further, the invention dynamically provides an opportunity to the requesting entity to purchase unauthorized functionality. In this manner, functionality within the software product may be enabled or disabled at any time (e.g., during installation, post-installation, and re-installation).