Casting this spell allows you to prepare additional spells or retain spells recently cast. Pick one of these two versions when the spell is cast.
Prepare: You prepare up to three additional levels of spells. A cantrip counts as 1/2 level for this purpose. You prepare and cast these spells normally.
Retain: You retain any spell of 3rd level or lower that you had cast up to 1 round before you started casting the mnemonic enhancer. This restores the previously cast spell to your mind.
In either event, the spell or spells prepared or retained fade after 24 hours (if not cast).