Well back in Atlantic City prior to the close of the Atlantic City Hilton (previously was Bally's Grand) our casino hosts used to walk around and hand these out for extras, besides all the comp they arranged, etc.
Sure we had promo chips, which were always play until you lose, unlike todays, one time use style.
We used these primarily at the gift shop or restaurants when we didn't want to get a hold of a host or we could give them to our non-comped friends. They were valid for any bearer.
Like I said, unlike today!