The honest lifespan
A good artificial lawn typically lasts on the order of 15 to 25 years. That is a broad range on purpose, because a quality turf on a proper base in a quiet yard can reach the high end, while a cheap turf on a poor base in a hot, busy yard may fall well short. Most people land somewhere in the middle if they buy sensibly and keep up with light maintenance.
Manufacturer warranties are a separate thing, and they are usually shorter than the real service life. Warranties commonly run in the 8 to 15 year range, and they mainly cover defects like fading beyond a stated limit or fiber breakdown, not ordinary wear. So a warranty is a floor, not a forecast. Turf often keeps looking fine for years after the warranty ends, and it can also start to look tired before then if it takes heavy traffic.
Treat any single number you see with caution. A blade of turf does not fail on a set date the way a battery does. It slowly loses its bounce, its color, and its full look, and one day you decide it no longer looks the way you want. Where it lands in that 15 to 25 year window is mostly decided by the choices below.