Stolen product and a copyright change

Hey all. I have 2 questions and if someone could help me with this it would be great.

First off, i have a product that i sell and in my license agreement i specifically note that all copyright notices in the product's control panel must remain intact. However i saw some of my clients changed them to their own... Now that's something that violates the license agreement. The question is, is it worth it to persue any sort of compensation? If so, where to start? Should i take screenshots, clients' info, etc and then pass them on to my lawyer?

And a second question. I also caught one of my clients installing my product to different domains (in the license agreement i state that for every installation of the product, a new license should be purchased) and once again using their own copyright in the control panel instead of mine. Now this seems like my client decided to do business with my software and sell it (rent it, lease it, give it away) to somebody else without my permission as if it was theirs. Same question as above, where to start in order to legally persue this matter?

Thanks

I don't know how to persue this. But let me ask you this - is it worth it to you to chase after 2 clients?

Also, have you tried contacting the 2 users?

I haven't contacted them yet since i thought i would figure out what i'll need before i take any actions. So in case something goes wrong i'll know what to do.
Also more than 2 clients have changed the copyright notices in the control panel.
And so far there is one client who seems to redistribute the copy which is what really bugs me. I wouldnt care if they made it "warez" like, but they get money for my work...

Get in touch with them, don't make a big deal of it this time just point out that they are in violation of the licence agreement and ask them to reverse any changes they have made. By all means collect some evidence before you do this and if they continue to violate the agreement decide whether it's worth your time and money persuing it.

You may want to keep in mind that screenshots, although good, can easily be modified. Try to collect evidence that is 100% proof positive.