A memory is easiest to retrieve in the same setting your mind filed it away in
Endel Tulving and Donald Thomson proposed in 1973 that memory stores not just a fact but the cues present when it was learned, so recall works best when those same cues reappear later. In their experiments, people did worse recognizing a studied word when tested outside the pairing it was learned in, even though they'd seen that exact word before. The 'encoding specificity principle' explains why returning to a room can suddenly jog a memory that felt completely gone elsewhere.