long-term memory

memory of things that occurred a long time ago

Long-term memory (LTM) is memory, stored as meaning, that can last as little as 30 seconds or as long as decades. It differs structurally and functionally from working memory or short-term memory, which ostensibly stores items for only around 30 seconds.  Biologically, short-term memory is a temporary potentiation of neural connections that can become long-term memory through the process of rehearsal and meaningful association. The proposed mechanism by which short-term memories move into LTM storage is via long-term potentiation, which leads to a physical change in the structure of neurons. Notably, the time scale involved at each level of memory processing remains under investigation.
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Noun
1. your general store of remembered information
(synonym) LTM
(hypernym) memory, remembering
(hyponym) episodic memory, personal memory

the immune-systemis ability to remember and defend against foreign proteins when challenged; certain vaccines are better at inducing long-term memory than others (the tetanus vaccine, for example, as compared with influenza vaccines).