They do not forget! I had Comcast/Xfinity from 2005-2022. They wanted to charge me for an old cable box from 2005 that I didn’t have when I cancelled service. Turns out it was in the back of my garage and super rusty but they accepted it. They also said that while they would charge me if I didn’t have it, they are going to throw it out as it’s no longer supported and corroded.