I've been using a small free program called hostess that edits the Windows host file. The host file is somewhat like a firewall in that it can block outgoing requests from programs that you are running. With the correct URL for the program you are running, you can block the program's request to contact its publisher's website for license verification.
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http://www.youtube.com/watch?v=aFJ54yOuQGg
Hostess
http://download.freewarefiles.com/files/hostess41.zip
Prank - Using the Windows hosts file to redirect sites to another
http://www.youtube.com/watch?NR=1&v=RrFg5OZX8lk&feature=endscreen