Cats going potty inside

I am so stupid. Im just now realizing my cat has been peeing in the kitchen and area near dog food bowls for years! Mainly those areas. I do know about a couple other places that happened once in a great while. My last dog passed away and I started realizing it wasn't their slobbers i was seeing. I was ocd before so of course we didn't smell it. He was at the vet and good. Im gonna get another litter box for downstairs as well now. His name is JJ, short for Jack@$$ Jr, and he is DEFINITELY playing the part now! Please any advice?