>>You may try the hard disk serial number. You can use my DriveInformation
>>class to extract this info (downloadable from the Files section, here on
>>UT). This is "unique enough", but it will change if the user formats the
>>drive.
>>
>>Another unique number is the serial number of the network card, but I don't
>>know how to get it (and not all computers have a network card :)).
>
>Neither would do. I've seen a scene, a couple of times, where the key
>was connected to the hard disk serial number, and the OS was upgraded
>from DOS 3.x to something newer, and it required formatting, or the app
>was simply moved to another disk when the original disk was too small.
>The app was not functioning anymore, because the disk number has
>changed. The programmer who did it was unavailable, and it would be
>quite undecent if I tried to reproduce what the users had to say.
>
>One'd better weld it to user's name (as written on the check), and have
>it visible at app start. This is quite common practice, and is machine
>independent.

I'm protecting my software by using a company's name the date, whether it's a Demo, Hire or Full system and single user or multi user. According to this info i build a code. This code is linked to all the above varables. I then store all this info in a memo field and hide it in the windows system directory with a name windows like name.

If my clients installs my app, he is promted for a activation code. He faxes me hes registration and i fed his info in my app. This way a can track my systems as well as my clients using my software.