What should I do if I forgot to turn in a hotel room key card after checking out?

Other businesses use such cards for employee access and I have known some impose quite hefty charges to replace lost cards (say $20). However this may be more to discourage the security breaches and administration involved than to cover the cost of the card alone, which for bank cards is under a couple of dollars (and bank cards are likely more expensive than hotel cards).

Hotels cards are normally only valid for the duration of a stay (in Jakarata I had one that expired every few days!) so there is little security risk as at check-out a card valid up until then should be invalidated anyway, until 'recharged'.

You are supposed to return them and even $5 is probably a lot more than the cost of postage etc (in country) so I have posted a card back before now. However I admit I did not bother when one turned up after I had left the country.

... though some make a point of collecting them!

Hotel keys are coded for the length of your stay, they will usually expire around check-out time on the last day of your stay.

Some hotels will ask you to return them because even keys which no longer open a particular room may still be used to access other key-card secure areas like the pool, business center, or gym.

Basically though, the hotel buys keys in crates of several thousand, and expects that most guests will not bother to return it. Since many hotel keys include the name and location of the hotel, I always think of them as a 'free' souvenir.

I'm quite forgetful, and at one point in my life was traveling about 20 weeks out of the year on business. I regularly forgot to turn in hotel keycards. I called a couple of times and was told not to worry about it, so I stopped bothering. You'll notice a couple of things. First, they don't ask you to return the cards at checkout. (At least, traveling in the USA and Canada as I did, I was never asked at checkout to turn in a keycard.) Second, they are typically emblazoned with the hotel logo and the name of the hotel.

Now, the older punchcard keys (the ones with holes in them) and of course, regular keys are a different story, but with the newer keycards, I'm going to say that most hotels simply find unreturned cards to be a source of cheap advertising.

Nothing, you can keep it as a memento.

Last year I travelled to Singapore with my friends, our return flights were different and I was the one who checked out last from the hotel. When the receptionist asked me about the other 2 cards, I told her that we lost them somewhere. She said no problem and wished me a happy journey.