I agree with the contention that the images enhanced the mind's ability to perceive similar images and that is what constitutes memory. There is no storage from what I can see.
This makes sense to me. Epicurus was arguing against any inborn memories like Plato so he needed the mind to perceive existing images. Even the prolepses appear to have been based on repeated exposure to concepts and things. This grooves those mind passages to be able to recognize justice, a cow, Plato (
my phone autocorrected there as "potato"!). Now, this ability could take place as infants even... I don't know if a text says this, but that would allow infants to acquire prolepses and memory without their being born with those things from a previous life or from some supernatural soul corral. Epicurus needed a fully physical procedure for memory with NO supernatural input and this seems to be what her hit on.