I don't think anything from IKEA is designed to last. I think Aerons are guaranteed for twelve years.
FWIW, my parents' home office is pretty much 100% IKEA and it's all in good condition, despite now being almost exactly 10 years old now. Only niggles are how the colour of the wood veneer fades (or rather, darkens) with exposure to sunlight, and the worktops of the desks have developed a series of minor dents and scratches, thanks to being made of softwood.
My Aeron chair has a 12 year warranty, yes.