How options actually work on binance?

So, often when shopping for bitcoin I arrange buying orders at specific prices. I was talking about this with a pal who buys shares using options, and he stated:

You can sell places on the strike you needed to purchase, if the worth is on the cash, you buy the asset on the worth you needed, if its out of the money you get the premium.

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