It's explained a bit more elsewhere. Somebody sold Mrs. Lemon a CD of the Digital Tradition, which is available for free download. The CD also included other programs, but those programs wouldn't operate unless she paid a fee for a key code to unlock the programs.
If you produce a copy of the Digital Tradition for somebody, it's OK to ask for something to defray your reproduction cost, but it ain't fair to sell a free program.
-Joe Offer-