I doubt they were used in a poker tourny.
They are not gaming compliant.
Compliant would have denoms, NCV, or both on each side, Las Vegas on one side, Caesars Palace name on both sides.
IMO, those chips are souvenir chips as they do not have to have gaming approval.

That said. Things were a little different in 1981. Gaming wasn't up everyones a$$ in those days over chips.
I think they were likely given away or gift shop.