Expire worthless
An option expires worthless when it finishes at or out of the money. The contract ends with no value, and the buyer loses the full premium paid.
At expiration, an at-the-money or out-of-the-money option has no intrinsic value, and with no time left it has no extrinsic value either. It is not exercised, it disappears from the account, and the premium the buyer paid is the full loss on the position. For the seller, the premium collected is kept and the obligation ends.
Many short-dated, out-of-the-money options expire worthless, which is the risk a buyer accepts in exchange for a lower price per contract.
Illustrative example (hypothetical numbers, not a real trade): a buyer pays $0.60, or $60, for a $25 call. The stock closes at $24.10 on expiration day. The call expires worthless, the buyer’s loss is the $60 paid, and the seller keeps the $60 collected.