At years of age, children realize they need to remember some things, and they try to do so, usually via rehearsal (repeating an item again and again). this is not the most efficient strategy, but repetition can lead to automatization.

I believe the answer is 5-7 years old.
Up to this point, the ability to store long-term memory has started to develop. This stage is very crucial for most parents because if the children does not receive proper accommodation during this period, it would be very likely that the children will grow up with learning disabilities.