I have raised veiled chameleons for 16 years and the oldest male was almost 9 years old. My females only lived to the ripe old age of 3-4 years at best. But I didn't have the benefit of this site to help me, and there wasn't that much information in those days. Had to learn things the hard way.
For example I knew nothing about lowering their calorie intake, or their temps to slow down their egg production. My first female had about 68 eggs if I remember correctly. It took a lot out of her I think she only lived about a year and a half. You just can't keep up with their calcium needs, and they become egg barren. And only 38 of the babies lived long enough to sell.