Question I've always had for WP Theme businesses: is there any need / common practice to prevent plugin piracy? Or is the market so big and pirates such a small portion of it that it isn't really something worth worrying about?
IMO, it would be counterproductive to employ any kind of obfuscation or license protection. Having access to the code is part of the reason people choose to build their sites on WordPress. More installs than not have some kind of customization done. Plus, you'll have less satisfied customers (inevitably a significant portion will have issues getting the loader/licensing setup to work on their shared host, or will have other issues you can't help them with because they can't debug the code) so less blog writeups / recommendations driving referral sales.
I was in the WP business for a while, with about a quarter million in sales before I sold it off, and did nothing to prevent piracy. It wasn't an issue. Someone pirating the code doesn't hurt me. Anyone that wanted the plugins/themes and had money was going to pay for it, as that's the only way they would get support and updates.
The people paying for your WordPress plugins and themes are, generally speaking, people who don't have time to fuck around with piracy.
I've experienced this first hand. As a junior web developer at an advertising company, there were plenty of times when my grand schemes for how we could do something for free on WordPress were met with "no, just pay for it".
Mostly echoing what others are saying here. When I deliver a wordpress site to a client, there is no way I am going to include pirated software. I don't want any sketchiness finding its way back to me. Also, I will pay for any software/plugin/theme that costs less than my time to build the same thing. It's just a matter of numbers. A $35 theme can get me 80% of the way to a client's desired layout. If I'm getting paid $500 for the project, then I'm making $465 for only a couple of hours of work, rather than $500 for several hours of work (starting from scratch).
It's like any other piracy as long as you take basic precautions you'll be fine. If you make something worth pirating generally it's worth buying, don't worry about the people who will never buy your product, worry about making the people who do buy it happy.
