In this set of API's there should be some kind of encryption of arguments and results, to prevent spoofing by the substitution of shared libraries. I am not yet sure how successful this can be while maintaining the openness of the system. Software licences are a network resource, and so we want a way to spread licence information throughout the network. Another key technology to look at is the recent work on digital cash. A floating licence system could be thought of as a small economy, with only a certain amount of cash in it.
Application programs can buy and sell the right to execute.
Conclusions Software protection is of concern to every software user, and technical means of software protection have the best chance of ensuring that illegally running software is as expensive as buying a licence. In the UNIX marketplace, FLEXlm is the most used licence manager. While it has many desirable features for a licence manager, it also has some weaknesses. There are some key technologies in use in the UNIX world that could contribute to the development of a better licence manager. We should remember, however, that there will never be a perfect licence manager.