A timber deck should be a long-lasting structure to enjoy for many years, so long as the right materials have been used to construct it and it is maintained effectively during its lifetime.
For peace of mind, we would always advise you to choose products that conform to the TDCA DeckMark Quality Scheme or decking which comes with a performance warranty of between 15 to 25 years, depending on the supplier.
Take note of the terms of the warranty and keep your records safe.
Most importantly, your timber deck boards and indeed all of the timber used in the construction of the decking, should be sufficiently durable to provide long term performance in outdoor use. It should be made from either appropriately pressure treated softwood, chemically modified or heat treated timber or a hardwood/softwood species with sufficient inherent natural durability.