People use facial expression to help recall an emotion, for example, re-enactment of a smile helps in remembering a smile.

Researchers found that performance on the memory tasks with the face in blocked condition was significantly worse than with the face in 'free' condition. They also confirmed the hypothesis that 're-enacting' the motor pattern associated with the emotion helps to recall that emotion.
Raffaella Rumiati, another SISSA professor said, "This suggests that even during the storage phase of memories, people also encode the motor information and re-use it during retrieval."
Source-Medindia