If a functionality is explicitly created at runtime, it may need to be explicitly disposed. Web ADF implementations of IGISFunctionality merely use the Dispose method to set the initialized flag for the functionality to false. As a result, it is not necessary to call Dispose. However, if creating a custom data source with a functionality which needs to clean up resources when its work is complete, implement the Dispose method and call it explicitly at runtime.

Reference

IGISFunctionality Interface

IGISFunctionality Members