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

https://jasperotbu571.iamarrows.com/should-the-manufacturer-survey-the-deck-before-quoting

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 material failure, not wear and tear or damage from weather