Originally Posted by HarryT
You may perhaps misunderstand me. I'm not expecting to be able to find out who is using my software illegally. I simply want a practical method of being able to prosecute those whom I do catch (eg selling copies of my software on eBay - that's quite a common thing, sadly).
I did misunderstand you. If that is basically what you want, i.e. a practical method to go for the people who try to get money out of your work and don't give anything to you, you certainly have a good point.