How options actually work on binance?

So, often when shopping for bitcoin I set up shopping for orders at specific prices. I used to be talking about this with a pal who buys stocks using choices, and he stated:

You may promote puts at the strike you needed to purchase, if the worth is on the money, you purchase the asset on the worth you needed, if its out of the cash you get the premium.

Wich is cheap, I did a check with a small sum of money and bought a put, however because it was out of the cash the the contract expired I solely stored the premium, what occurs if the contract expires on the cash?