Single ply roof guarantees usually last 15-20 years, but the actual roof can...

https://www.bright-bookmarks.win/single-ply-roof-guarantees-usually-last-15-20-years-focusing-on-the-product

Single ply roof guarantees usually last 15-20 years, but the actual roof can often go on for 25-40 years with the right care. The guarantee covers materials and workmanship but not wear and tear or damage from neglect