Ultimately the only truly useful answer will be from a lawyer who specialises in copyright in the relevant jurisdictions (probably wherever it is going to be published, possibly also where the photographs were taken).
That said, I think the general concept you're looking for is whether it's Editorial use or Commercial use. The former tends to be things like newspapers, magazines, and other such newsworthy or documentary uses, while the latter is typically "selling/endorsing a product".
Editorial use typically requires just permission from the photographer, while Commercial use requires model releases as well. This is what allows journalists to publish photos of people (it would be impossible to have photos of any crowd of people in a newspaper without such exemptions!).
Something like a memoir might be a bit of a grey area, but I can see an argument that if it's essentially just a factual, historical account, that it would fit under "editorial" use. I think one of the key aspects is whether the people in the photos would be assumed to be endorsing the product—so if it's clear they're people in or related to the story, I suspect a model release isn't required.
Again, a lawyer's really the only safe way to be sure, but here are some resources that (to me) suggest you probably only need photographer permission (which may or may not have already been given, along with the original photos)