How long is durable life of futons?

Generally speaking, if used daily, a mattress will last three years and a quilt five years.

However, this depends on how you take care of it.
Every morning when you wake up, you should remove the moisture from the underside of the comforter and expose it to the sun once a week to restore its elasticity. It may last longer if you do so.

If the sun does not restore the fluffiness and it is no longer comfortable to sleep on, replace it with a new one.