Memory aid means not every memo or note is copied (8)
I believe the answer is:
mnemonic
'memory aid' is the definition.
(I've seen this in another clue)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for mnemonic that I've seen before include "Letters aiding memory" , "System for improving memory" , "Device (such as an acronym) used to aid recall" , "Verse or other aid to help one remember facts" , "Aid to remembering" .)