>Back to my original question. Assume I was writing classes that worked along side of MS Word and MS Outlook. My class hierarchy
>might look like this http://www.marois-consulting.com/Files/hierarchy.JPG. (This is just an example, but it resembles what I was
>thinking). Each one of the objects in this image would be in their own project in the solution.
>
>When I compile the class "Outlook2003 Extensions", in the bin folder you would see:
>
>Outlook2003 Extensions.dll
>Outlook2003.dll
>Outlook2000.dll
>OutlookBase.dll
>OfficeBase.dll
>
>Now assuming that I was creating a product to market called "Outlook2003 Extensions", and each child built upon its parent, then what's stopping someone from instantiating Outlook2000.dll and using the functions in it, even though they might not have purchased
>the Outlook2000 module?

Viv provided info on how to add security. But, I am not sure you would be able to embed all that into one file.