|Credit: Moshe Roytman|
Depending on what "chess activity" means -- we start counting here (see the link) from his first public chess activity, a solver of a problem in Davar in 1937 -- at a relatively late age of 22. Assuming he had played in tournaments before that, perhaps as a child, this would add at least 5-10 years, making a record of ca. 85-90 years of competitive chess, surely close to a world record.
Moshe Cna'an, a well-known chess enthusiast, noted that in one of his last two tournaments, Pe'er player a 9-year-old (age difference: 91 years). Nissan Levi organized the event. We note that Pe'er had very kindly given us much material for this blog -- such as the following item.