This set says All rights reserved for me unfortunately.
I believe that this is just what Behance posts things as by default, and in some cases Mike/Beeple never changed it. You can see a conversation expressing concern over this elsewhere in this thread, but the long and the short of it is: I emailed to ask if I could pay licensing fees or if I should switch out some of his images in some games; he hasn't gotten back to me; but he did get back to someone else who emailed him, and said to that person to feel free to use any of his everydays.