A single ply roof guarantee usually covers 15-20 years, but the actual roof can...

https://melissafreshmaid.com/tpo-vs-pvc-lifespan-what-matters-more-than-the-material/

A single ply roof guarantee usually covers 15-20 years, but the actual roof can last 25-40 years with the right care. Guarantees mainly cover materials and workmanship, not wear and tear or damage