I am curious about how do you protect your software against cracking, hacking etc.
Do you employ some kind of serial number check? Hardware keys?
Do you use any third-party solutions?
How do you go about solving licensing issues? (e.g. managing floating licenses)
EDIT: I'm not talking any open source, but strictly commercial software distribution...
There are many, many, many protections available. The key is:
Nothing is unbreakable, so it's more important to gauge these things and pick a good protection than to simply slap on the best (worst) protection you are able to afford.
And variations of the above.