What are the reasons and causes for magnetic striped keys to become demagnetized?

Question

what are the best recommended keys cards to use for hotel purposes?

Answer 1

Most of the time they come in contact with another magnet and it screws them up.  Magnets are found in all electronic things like Ipods and cell phones, but people don't realize that they are in there.

Answer 2

Micro electronics don't generate enough of a magnetic field to affect the magnetic strips on cards.  The kitchen magnets, like the ones on the refrigerator, will wipe a card stripe if the magnet is laid on the card, even on the opposite side, but it does have to be virtually on the card to do it.  Another mistake that people make is laying their card down at the store on the magnetic RFID anti-theft disabler.

I don't understand that last part of your question.  What is a hotel purpose?