Writing things down is the best way I’ve found to remember things. Not so appropriate for a young child maybe

How old is your child ? In what area is his memory affected ?
Does he get help at school and home ? Think this is a question for his therapist. I assume he regularly sees a neurologist ? When you struggle in everyday life with the effects of his epilepsy on his functioning, then there’s certainly reason for support of a therapist working with him.
Memory games, puzzles, making music, singing etc are always good.

https://www.understood.org/en/school-learning/learning-at-home/homework-study-skills/8-working-memory-boosters

this website has some useful information on it. good luck

play memory card games and just provide stimulation

make up songs and games and find out how he learns best, seeing ,hearing, talking, feeling because children learn best in a certain, individual way

Lots of visual aids, memory games etc. How old is your child? Writing special stories, or drawing pictures at the end of the day to remember what happened during the day may help as well

Memory games, flash cards, poems and songs.

Memory game, you can get little cards now in all different types of images ie fairies, dora etc.

The board game called memory is a great memory game, playing pairs with a deck of cards too.

I would also if you haven’t already put her on omega(fish oil capsules) as it is good for the memory as well

Using some simple games with items around the home can do wonders for a child’s memory. If you can make learning fun, and do it often, you’re more likely to succeed. You may also find the following page helpful …

http://learningworksforkids.com/2013/04/5-tips-to-improve-working-memory-skills/