download security

I have software I can sell by disk (requiring no password). I am nearly set up to take credit cards. How do I allow a customer who has paid by internet to take delivery by internet?

Licensee might (1) Be given access to a limited part of the website, to download the program; or (2) Be given a download demo which can be made fully functional (de-crippled; I know how to do that) by password. Or what have you.

But I do not want a fixed password; not safe. I could keep a record of every unique password by user name; would rather convert the user's name into a typeable password, or issue a random temporary password (and issue another if they lose the download).

I need VB code or pseudo code.

This cannot be a new problem; but I cannot get any info anywhere on it. Even a good reference on the subject would be greatly appreciated.

See if either of the following help:

http://www.freevbcode.com/ShowCode.Asp?ID=1639
http://www.freevbcode.com/ShowCode.Asp?ID=2232