[anukriti]

"I am no expert on memory, but from what I have read on the topic, our long-term memory is virtually unlimited, the main constraint being inability to recall rather than the memory content being erased. If you have once learned a topic well but haven't visited in a long time, you may not be able to recall it very easily, but you will be able to recognize or relearn it better than someone who doesn't have any exposure to the topic. "

I agree with your this part and personally my memory behaves the same way, but I am not sure if it should be like this, because then for example if I am having a conversation with someone about a topic I studied long back but did not recall recently then I am unable to contribute anything to the conversation although back in my mind I know that I studied or read about this but because of this poor memory thing I have to remain silent.