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

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.

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.

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.

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!

Recycle the card however you wish. Those things are ephemeral and can’t be used anyway after you check out and the hotel probably buys them in bulk.

And by “can’t be used”, I mean that your checkout date is encoded onto the card key and the room locks will reject any attempt to open the door past an expired checkout date in the same manner that you can’t open someone else’s door while you are at the hotel (or your own effin door half the time while you are still checked in).

That does not mean these keys can’t be re-programmed with new room or checkout information. If you pay attention you will see the desk clerk shove the room key into a small box with a numeric key pad and hit a few keys et voilà you have a freshly programmed key ready to use (again). However if the key is physically damaged and won’t take the reprogramming then the next stop is for it the rubbish bin. Here is a random link that claims to explain how these keys work Hotel Card Key Systems Explained

This of course raises the question of how easy it is to program a key in order to enter a room that is not yours. The funny thing is that while obvious, this question is actually moot as it is trivial to attack the lock itself with a simple electronic tool that exploits a fundamental design flaw in the how the locks themselves are programmed. Such a tool allows you to open all such locks with ease. I’ll leave tracking down that exploit to the interested reader

Hotels are aware of this flaw, but it is going to be a long time before they roll out new door locks for every door that uses this style of pass key. Especially as a lot of hotels can’t even seem to keep up with regular maintenance of normal in-room equipment.