From the Snopes article that "debunks" it:


Is it nevertheless possible that personal information could be encoded on hotel keycards? Certainly, especially at a non-chain hotel — an unaware (or unscrupulous) hotel operator might mishandle personal information provided by guests. As the Las Vegas Review-Journal reported:

Deputy Attorney General Tracey Brierly saw it with her own eyes in South Lake Tahoe last month.

Brierly, a deputy attorney general in the Bureau of Consumer Protection, attended a High Technology Crime Investigation Association conference in South Lake Tahoe in late October.

The speaker asked for volunteers to provide their credit-card style room keys, the ones with the magnetic stripe. Five or six people provided their keys, and the speaker swiped them through a credit card reader.

"Two of the keys brought up a name and partial address, and another one brought up a name, address and credit card number," Brierly said. "I had no idea this was even a possibility."

Brierly said she didn't know which hotel keys had the embedded information, saying she typically leaves the key in the room upon checkout, but won't any more.


Better safe than sorry. Keep the keys and destroy them.