Very late to the party... but IMO, the bottom line is "No, free or otherwise, you can't"

It may be possible to so obfuscate the code (and not just in the Perl-ish sense) that reconstructing (reconstructing, not extracting!) is inordinately costly in $$$ or time for most pirates/thieves/curious/whatever (<= pick one or more) than writing new code after deconstructing your API (if any). But that's !eq to impossible.