How long does a silicone sex doll last?

Longer than TPE, and mostly it depends on storage rather than use. Silicone is chemically stable — it does not lose oil, soften unevenly or turn tacky the way TPE does over the years — so it ages through wear and pressure damage instead of material breakdown. Stored properly, with the joints relaxed and no constant weight on any single point, a silicone doll stays presentable for years. Stored badly, folded or under pressure, permanent deformation can appear in months.