It depends somewhat on the target audience. When you're creating systems for corporations, piracy will tend to be far less of an issue. Companies tend to be highly risk-averse, when it comes to being sued for copyright infringement. On the other hand, individuals tend to view themselves has having a very low chance of getting caught, and expect the consequences to be negligible ("Okay, ya caught me, here's your $50").
With corporations, it generally doesn't take a lot of copy protection to finish securing it, as that will finish the discouragement process. If you have frequent product updates, so much the better (nobody wants to recrack a program every month).
With individuals, there are a few considerations worth having.
1) Are the pirates actually lost purchases, or are the just bums who were never going to buy your software anyway?
2) Is your contemplated anti-piracy scheme likely to drive away potential customers (Sony's SecuROM DRM comes to mind). This can range from security risks to annoying your customer all the time
3) Is your contemplated anti-piracy scheme flaky? I recent fought with a company for 3 weeks to get the demo of their software functioning. When their software demo won't function, I'm not inclined to buy.
4) What is the nature of your software? Blizzard doesn't have many issues with piracy, because you have to log into their servers to play their games. The best part of their games is the online experience, so it isn't much of an issue. Some of the text editors out there, by contrast, exist solely on your computer. They function fine with your firewall blocking internet access, so they're far easier to pirate, by nature.
5) Is your pricing pushing people to pirate your software? We all know that Photoshop gets pirated like crazy, because hundreds of dollars is a lot of money to play around with it at home. By contrast, pirating Plants Vs Zombies at $15 seems kinda silly. I find it interesting that Good Old Games (http://www.gog.com/ ) offers completely DRM free games for download, yet doesn't seem to be having massive issues with piracy.