Most hotels do impose fees, usually $20-$50 per key not returned at checkout. Save yourself the surprise by proactively reporting any lost or missing keys to the front desk. And remember – key cards are essentially a deposit required to access your room.

For the vast majority of modern hotels using standard plastic RFID or magnetic stripe "swipe" cards, you will not be charged if you forget to return them. These cards are considered inexpensive consumables, costing the hotel only a few cents each, and they automatically deactivate at your scheduled checkout time. In fact, many hotels encourage you to keep them as souvenirs or drop them in a recycling bin. However, if the hotel uses physical metal keys or specialized "designer" wooden or heavy-duty RFID fobs, they almost certainly will charge you a "lost key fee," which can range from $25 to $250 depending on whether they need to re-key the physical lock for security. Always check the fine print on your registration card; a small number of boutique hotels or international properties may technically list a $5 fee for unreturned plastic cards, though this is rarely enforced unless you lose several during a single stay.