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

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

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