The guarantee for rupture is 10 yrs for CUI and lifetime for natrelles, that doesn’t mean they would need replacing after that 10 years. Life in general will have an effect on them, ageing, gravity etc, same as with ‘real’ boobs, but there’s no time limit on how long they actually last, it’s just the guarantee that comes with them purely for rupture. Like anything, they can last much much longer and you may feel that you don’t want to replace them for some time, if at all.