Since we're not allowed to post links on here, I found this and just copied and pasted it here. You can find this info ALL OVER the internet.
4. What is the expected product life of the implant? How long do breast implants last?
A 'guesstimate' for the product life is 15-20 years - averaging at 16 years ( Institute of Medicine). Implants do not need to be changed unless there is a deflation. Although one may consider changing a silicone-filled implant out after this amount or more time has passed to decrease the chances of a rupture which would necessitate a silicone gel/oil removal procedure.
There is a 2% rate of deflation in the first 10 years. Although "wear and tear" will be different in each individual depending upon implant surface type (textureds may rupture sooner or more often than smooths). However there are women who have had implants in over 25 years with no problems. There is no definite answer, but do expect to replace implants at last once in your life.