Photos - "You have a new memory" "You have a new memory"...
No I don't, I have the same dodgy recollection of the past that I always did.
"What was for dinner yesterday?"... not a clue unless I look at the dribbles down my shirt.

Anyway, Photos seems to think I ought to be reminded of people &amp; places I haven't recalled in years &amp; announces out of the blue, "You have a new memory"... 

I click on it &amp; I'm greeted with an image from 2007, of my partner.
Well, honestly I do remember who she is, I'm not that bad - in fact I just saw her, seconds ago, she's still fine...

...but when did Photos turn into Facebook &amp; decide to prompt me with this kind of thing?

More importantly, how do I switch it off?
Not just the notification, I want it to simply not do that.
I'm not still at school, taking selfies &amp; pictures of my food every day, I don't want my professional environment besmirched by 'social media'-type actions.

Plus points for how it's actually doing this. Does it just flip a coin &amp; present me with some random picture, or is it more insidious?
I don't have any photos stored or shared on iCloud.

[Facebook, you'll be happy to know, I dissuaded from this kind of thing years ago. People still use it to try to contact me... eventually they'll learn ;-)

 btw, question is a somewhat flippant rant [look up Victor Meldrew, or One Foot in the Grave], answer is still important ;)

In a more serious tone - how does this sit with GDPR?
I didn't opt-in to this.
Hum...
Even though I think your question is actually not a real one - you seems to know that Apple tried to implement a Facebook-like feature and made it impossible (or really hard) to disable, a piece of answer is that Photos is not designed (in my opinion) for a professional use.

Photos is intended to store photos of your family, your friends, your trips and holidays or other annoying every day's stuff like that. Every feature is design in this purpose: moments, collections, faces, locations as well as shared albums and ... memories!

I'm afraid you only have few solutions available including turning of memories notifications you mentioned (and never tap the memories album again). If you don't want [your] professional environment besmirched by 'social media'-type actions you may have to choose a different photo app to separated your professional and private life.

Concerning the algorithms behind memories, it is obviously based on similarly between groups of photos (location, date, people...). From my personal experience 2 différents types of memories are highlighted by the App: 


Regular memories that gather photos from a recent event (a trip, a week-end, a party). They are usually pushed froward few weeks after the event ends.
Special memories that are usually highlighted many month (sometimes years) after the event ends. Such memories could contain only photos of a specific person (the memory titles "[Person X] over the years", "[Person X] birthday", [Person X]'s Home) or photos taken a specific amount of time ago (a have a "5 years ago" one, here are some other examples: "last Winter", "On this Day", "Chrismas day", "Halloween" and even "Best of Last Week/Mounth/Year").


I guess that you dislike this second category. This is quite intrusive I reckon but Photos App IS a social App since Apple designed to encourage photo sharing and viewing between family and friends rather than for professional use.