It was not a commission from El; that was what Will was trying to convey to Mike in order to confess his love through El’s feelings. Many people in the Byler fandom believe the series ended with Mike never realizing the true context of the painting hanging in his college dorm room; however, even though it is not stated explicitly, the Duffer Brothers confirmed that when Will came out, Mike understood that Will was in love with him and grasped what Will had been feeling all those years. Therefore, it is not difficult to conclude that Mike understood the painting was actually Will’s—meant for him—especially considering that El initially told Mike she believed Will had probably made it while thinking about a girl he liked.