Single ply roof guarantees typically cover 15-20 years, focusing on material...

https://daisydustmaid.com/overlay-vs-full-replacement-for-a-single-ply-roof-when-does-overlay-make-sense/

Single ply roof guarantees typically cover 15-20 years, focusing on material defects or installation issues. But the actual service life can stretch 25-40 years if the roof is well maintained