To remember things, or to bring things up from the past. It usually means remember the pleasant things, rather than bad or evil memories. When I was younger, the voice on the radio would say, "And now, a walk (or stroll) down memory lane." , after which they would play an old song, at least three or four years old. It is not used as much any more, but people still understand it. It is usually sarcastic when I hear it these days.

It means to reminisce.