Some shareware programs open a "keyfile". If this file is valid, then the program is unlocked, and may display personal details (such as name, or email address) somewhere in the program. Maybe in the About window, or startup screen. But programs are often different, so some may save in s:, some may save in progdir: (the dir the program is run from). When the author sends you the keyfile, I'm sure he will give you details on where to copy it to.
