Single ply roof guarantees typically cover 15-20 years, but the actual roof can...

https://www.jelly-bookmarks.win/single-ply-roofing-guarantees-typically-span-15-20-years-covering-material

Single ply roof guarantees typically cover 15-20 years, but the actual roof can last 25-40 years with proper care. The guarantee mainly protects against manufacturer faults, not wear and tear or poor maintenance