Using a license manager can and should be the foundation of a successful sales/business model. Software demo functionality can maximize control and flexibility by including limited functionality for software evals and demos that are not yet activated. You can also up-sell marginal users, disable features and more.
The ability to easily create eval/trial/demo versions of your packaged software is arguably one of the most powerful advantages to using a license manager. Using an electronic license with an expiration date, and possibly a demo flag, makes your product accessible to would-be buyers. Since electronic licenses can also be easily turned into full, purchased licenses, a trial version of your product is the logical first step in a successful sales process.