With "Dynamical Passwords" you may generate passwords on any date (even each day).
There is no need to remember or save all these generated passwords as far as you can remember you personal password (key) and the date.
It is also useful for discovering weak links in a complex security system with many passwords protected elements / units.
The passwords are not saved so they can not be discovered in the case your hanheld device will be lost or stolen. | 
