Unidentified Coin. Un And A Map On Both Sides

Maybe some kind of token, souvenir item or game piece? Certainly not a coin (and while the photos are nice and clear, the size might be helpful).

No. People don't become members of the United Nations, nation-states become members.

Given the wear, and the pattern of wear, my assumption would be a slot machine or vending machine token of some kind.

While in theory using "UN tokens" to operate a vending machine on UN venues makes sense, in the same way that the UN has its own postage stamps for use on UN venues "makes sense", to the best of my knowledge, the UN doesn't operate any vending machines.

My next best guess would be a pachinko token. Just because it has "UN" on it, and the United Nations logo, doesn't mean it was actually authorized and issued by the United Nations. Somebody might be taking their name in vain. I would tend to assume that a legitimate "UN token", if it had the UN logo on it at all, would have a better, more high-resolution version of it. This one looks mostly right at first glance, but is somewhat stylized.