If you do not want the work stolen or used by people….then
1. Offer Encrypted source files at various points….and various payment level
The less the encryption = the more the cost.
If you have your own add ons…..like sliders and such…..then encrypt those.
These themes will be stolen and rebranded. They will be modified and morphed…..
Eventually they will be in the wild and free to use!
People will resell them – they will use em free and such after purchase. However, if your work is cool – enough to be charged for – then someone will buy it….make a note of it and if you want to get a job as a web designer or whatever – your portfolio should make note of how many times it was stolen morphed and copied as a badge of success…..not a bad thing…...