I'll throw my hat in the "mostly just ignore it" camp. I work for a small software company and we have basic license key protection stuff, but our philosophy is

I'll throw my hat in the "mostly just ignore it" camp. I work for a small software company and we have basic license key protection stuff, but our philosophy is "someone who is pirating the software probably isn't someone we want to bother with as a customer anyway." Only a small percentage of people who pirate it are likely to be paying customers if they couldn't pirate it. So the real revenue loss is likely minimal. (Without know more about what the software does it's hard to make generalizations about the target market, though.) And you never know when someone who was able to use/learn the software by pirating it will be in a position to turn around and recommend to their employers or friends your product and those entities will actually buy it. If there's a specific site or forum online where the crack is being distributed, you can always at least just send a DMCA takedown notice, but overall it's probably not worth spending much time or money worrying about it unless you have real data showing significant missed revenue opportunities (which is at most a tiny fraction of the number of people who pirate the software). If you can update future versions of the software to not be cracked by the existing mechanism, BUT NOT AT THE EXPENSE OF CAUSING HASSLE FOR REAL CUSTOMERS WHO ARE UPGRADING, you could do that too.