I, too, find that I buy less and less during travels, and cherish photos and memories more than ever.
When my youngest son was learning (or should I say trying to learn) the French Horn, he practiced a piece called "Variations." His older brother opined that most of the variations were involuntary.
Is involunary memory like that? My Significant Other is writing his memoir of growing up during World War II and especially the days at the end of the war when the Russian army invaded their town and fighting broke out. As he writes and researches the history of the period, more and more memories return. Like going to an old boarded up well and discovering clear potable water. And now the memories come, bringing forth even more memories. It's an amazing experience, even to watch. And there is also the difference in what he remembers and what a younger sister recalls.
I found this blog which mentions memory in Proust, and thought you should read it, too.
It was tempting to call the post, Reading Proust in Oregon
The Other Odette