If a publication is set up with 2 certificates - one with a 2 day trail and the other fully functional when the serial number is entered, then can a user copy the disk and use the serial number with another disk? Is there a way to prevent that?
Two options to prevent users from sharing your serial number:
hardware-locked registration keys or software activation. Both solutions are handled by HTML Executable.
A sample is available at http://www.htmlexe.com/samples/hdlockedkeys/index.php
or use software activation as explained at:
http://www.protect-ebook.net/
or at
http://www.htmlexe.com/activationkit/