Daz renders are pictures, and they are just as much traceable as any other pictures.
I don't know anything about Daz including covert watermarks on thee pictures and that would not make much sense or meaning for them to do. If they did it, I think it woud be known already.

Considering daz content, as much as I heard from complaints of content producers, Daz does not give a fuck about piracy as there are plenty of 3d content sites and nobody cares. Nobody even bothers to complain about that. So that's one more reason why they would not do it. It seems that payment is totally voluntary here.