Several years ago, my kids and I all went to a concert and expected to meet the performer after the show - but a rude person blocked that from happening. We were all together for the holidays and that incident came up. My daughter said, "But we did meet him - we ran into him on the way out, all of us." I was sure it had never happened - so I asked her brothers. They agreed with me, it never happened. But their sister is just as sure that it did.
There's no way to go back and prove whose memory is accurate - we aren't on a TV show taping our lives - so whose version should be accepted? Does majority rule?
The last time I saw him, my brother mentioned how awful it was that our mother died alone in the hospital in the middle of the night (decades ago). I told him I was with her that morning, drove home where my husband said they'd called to say she was gone, and drove back. We both had clear memories of the day and his wife's matched his. However, two things backed me up: my (now ex-) husband and an official document with time of death that morning. We decided my version was probably more accurate.
This is one of the reasons it's so important to verify facts from multiple sources when writing non-fiction.
Memory may be fact or fiction.