Everything I buy or "take" from freebies (not too many freebies for me because I'd rather purchase) I enter into my database with the artist's name, file name, image, etc., so if I do use it I know who to credit. Not that I've ever used any of the models commercially, but just in case.

Poser 2, 3, 4, 5, 6, 7, 8, 9, 10, Pro 2014, 11, 11 Pro