The two who made it to 14 and 15 (died within 6 months of each other, after being together all their lives) were inside cat for the last 7 or 8 years of their lives. By then my mother no longer believed in letter cats outside.
One of those cats was "mine", but when I left home at age 20, she was 8 years old and I didn't think it was fair to take her away from all she knew and loved so I left her there. According to my little sister she missed me quite a lot, but I still think she was happier than she would have been, traveling with me.
My first cat as an adult, after I got settled in my new place was a little black kitten I named Blackberry, Bear for short, someone dumped in a parking lot. I still didn't know any better and I let him out after he was neutered. He came home the first time, but the second time, I never saw him again.
My next cat, and all after that, stayed inside.