Advice from good old shareware days (I never did any of this in my own shareware but have seen it many times): Defeat the crack when you put out new versions,

Advice from good old shareware days (I never did any of this in my own shareware but have seen it many times): Defeat the crack when you put out new versions, create more complex protection and obfuscation, but make the more complex check only after a few weeks of running the software. Most crackers develop a crack and when it works release the program, so any kind of delays and double and triple license checks defeat them for a while. Make sure to never tell the user "this software is cracked." Instead, make it fail with obscure errors or work only partially. Be surprised by the support requests you get from users of the cracked version. Put out your own fake cracks with complicated installation instructions that sort of work, but not fully, etc. Repeat indefinitely, with many releases. Do not ever use any intrusive DRM or hacks like installation of licenses in "secret" places, system modifications, etc., and make 100% sure your legit users have a perfect experience all the time. Basically, it's a cat-and-mouse game whose goal is to frustrate the users of the crack. At the same time, consider giving legit users better deals and more flexible pricing options. Maybe you can even give away older versions of the software for free or cheap. Finally, please remain polite even to users of the cracked version (they'll be on forums asking for help). Most of them simply do not have the money to buy a license, but might become legit customers later in their life when they earn more money. Some of them also aren't serious users, i.e., no future customers anyway.