[quote=@AliceInRedHeels]
Hmm, I take it they don't always gain a memory with each person they kill? Is it a random generation thing? I think the idea of it being more of a chance of luck then a know fact of kill someone= new memory would add to the desperation of those running low on memories?
[/quote]

You would likely just pinch a memory that once belonged to whomever was killed. If you kill an NPC, i'll generate something for you. It's a good way to find out the backstory of certain characters though.