What would you name a creature that feeds off memories??

The Never Born, The Eater Of Souls
Sphexe
Boswash
Graboid
Vjorn
Mugwump
Stobor

You need to read novels. Lots of novels. Any novels. Notice that they all have perfect spelling, perfect punctuation, perfect composition. Notice where they use one space and where they use two. Notice that every speaker in a dialog gets a new paragraph, and every paragraph is preceded by a blank line. Notice any writing techniques or figures of speech. Take notes so you know where you found what you know. It takes a lot of reading to be a writer.

(greek: μνήμη (mnéme); pronounce /mneemy/ = memory)

φαγεῖν (phagein), "to devour".

So, a "sciency" word for a creature that feeds off memories could be :

The Mnemophage

Or, you could take the latinised form: Memovore (vorare, to devour).