What we do is have a license file with a memo field. The memo field contains all the computer names (sys(0)) of computers that are able to run the application. When the application starts up, it checks the license file to make sure the current computer is listed in that memo field. Of course, the data in the memo field is encrypted.

The user license file is updated with a new computer when the initial install of the client application is done. This file can also contain the number of allowed licenses. So after the install program runs, another program runs that checks the allowed number of license, then checks to see how many sys(0)'s are in the memo field. If the number of sys(0)'s are < allowed number of license's, then the program get's the sys(0) of the current program and sticks it into the memofield with Chr(13) + chr(10)

Hope this helps.