From Yenly
When we learn something new, we are using our working memory. Our working memory is like a so-so blackboard with limited capacity to hold four Chunks. To move these chunks into long term memory, we need Delibrate Practice using Recall method. Spaced repetition technique is to spread out our repeating practices over a number of days to build stronger neural structures.
Learning and relearning is the way to set it into longer-term memory storage.