Bob: that is what Active Lock does:
1- You can disable some features and enable them when your user registers, by a Keycode you give him. That is what they call "CrippelWare" or so.
2- Make a demo/trial based on either a number of days the program is used, or the times it is opened.
3- If the user modifies the date in his PC, the program stops executing at all and gives a warning you can customize, like "date invalid, call 1-800-etc, mention error number 001-001"
4- If the user tries to re-install the program, it will warn him: "your trial period has expired, please register" or whatever your message is.

Give it a try!

[This message has been edited by Juan Carlos Rey (edited 12-04-1999).]