The title pretty much sums it up.

If you rub a balloon against your jeans, it'll stick to a wall, but eventually fall off. Can the same thing be said about magnets?

they will not last forever. the structures that give rise to the magnetism will eventually revert to an amorphous state. it'll take centuries usually unless you are extracting energy from the field then they'll do it much much quicker.

You can quickly kill magnets by heating them, by vibrating them, by putting them in an AC electromagnet (which rapidly reverses polarity).