A souvenir is a piece of a place carried home, read as a memory you want to keep close. Losing one is linked to the fear that a good chapter is fading.
Has this come up in your dreams before? What was going on in your life then?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.