The theory that elephants have good memories has been greatly exaggerated.  The elephant does remember many things, but its memory is not better than many other animals.  Well-trained elephants can learn and remember about 30 spoken orders.

A trained elephant obeys an order, even if it has not heard the command for a while.  But it is common for a circus elephant to slip up due to slight lapse of memory.  Like people, elephants remember those who have been good to them, and those who have treated them badly.Dick Rogers