I’m sure every pet is different, but here’s another vote for “He’ll probably have no problem remembering you.”
My parents have a Lhasa Apso - granted, they are pretty smart dogs to begin with - but she’s very, very protective of the household and the people within it. If she didn’t meet you as a pup, you’re a stranger, and you’re in for a fierce yapping at (hey, it’s effective, she sounds at least three times her size). My grandparents would visit very seldom, but because they came over often when she was just a pup, she never forgot them. They didn’t visit once for well over a year, but little Zoey still greeted them like old pals when they finally came back. Anyone else, she snarls and howls and yaps at until they leave her premises. How dare they, after all!
Anyway, my father once looked up some information on why she might do that, and I’m running strictly on memory here, so no cite, but IIRC he told me cats and dogs identify people by smell, and once that smell is stored, they never forget. (Similar to humans, like the Old Spice commercial: “Scent is the strongest sense tied to memory” yada yada - there is some truth to that - Old Spice makes me think of my grandfather, though I’m sure that’s not what they want me to tie my memory to!)
Incidentally, my cat (also named Sebastian, but she’s a girl) seems to rely on scent, as well - she adores my husband, but all other men frighten her. I’m not sure if it’s their giganticness, their deep voices, or what, but they scare her. Hubby did at first, but she got used to him and grew to love him above all others. Before she can even see my husband, he’ll be outside, and she gets excited and waits by the door for him to come in so she can tackle him with her nudges and leg rubbing. However, after she met his father and brother for the first time, every time they came to visit afterward, be they on foot or by car, just before they knock on our front door, her ears perk up, she sniffs the air, her eyes get wide, and she takes off into the bedroom, looking for a place to hide.
Our other cat, Kero, doesn’t count, because she loves everybody, but I’m sure she does the same thing. She’s just not as selective.
Hope your cat remembers you!