How long your silicone utensils last will depend in large part on not only the quality of the set you choose but also how well you take care of it. Generally speaking, however, silicone utensils are known for their hardiness. For example, silicone utensils can better bear the shock of going from extreme heat to extreme cold without shattering.
That being said, silicone utensils can scratch easily. And if you choose a set with wooden handles, you will have to be careful to make sure the pieces don’t split. These considerations aside, with a bit of care, your silicone utensils can last for years.