I don't know.  Scent memory, for humans, is about the strongest there is
(have you ever smelled new-mown grass and had it instantly take you back to
a moment in your childhood?).  Cats, although not so much as dogs, rely on
scent much more than humans do.  I think it's possible that he may remember
what his slave smelled like and remember his kitten days.

Hugs,

CatNipped

I wonder, I know dogs can remember people for many years, I've no experience
of cat being reunited.

That's the thing about microchipping. Until it completely catches on, so
that most if not all pet owners use them, it just won't occur to people to
check, when they see a stray, whether it's been chipped. It's really sad
that these cats had to live as strays for so many years before finally
being returned to their homes, just because nobody thought to check for
a microchip. I'm not even saying it's anyone's fault, because it's just
not something the average person would think of.

Seems like something visible should be done to indicate that a chip was
installed - otherwise, it just looks like a stray. I'm thinking of
something on the order of the ear notch that feral caretakers do to
indicate a cat has been spayed/neutered. But I can't think of any kind
of mark that would be obvious, harmless, and lasting. Perhaps cheaper
versions of the scanners could be developed, so that your average
animal rescuer (or any interested party) could have them on hand to
test strays. The microchip is useless unless somebody scans it!

Joyce