Since the Chinese had the shortest words for digits, their memory went the farthest. This requires a lot of effort and is quite suseptible to disruption. In this case, even though we don't know how memory works at the neurological level, we know that maintenance is needed to keep the memory usable. Infant brains learn to recognize the phonemes in their parents' language by selectively killing off cells in a certain part of the brain, allowing the remaining cells to become useful. Here, it is the permanent connectivity of the remaining neurons that produces the memory.
Maintenance is unnecessary.
In other cases, our ignorance of how brains store memories makes it difficult to guess whether a memory requires maintenance or not. Along with some other evidence, it seems that procedure memory is more stable than experience memory. This is exactly the sort of thing that no one knows. There is no bioelectic circuit to run current through. Rather, the electric nature of the neurosystem comes from interactions between individual neurons.