It is not recommended to use contact lenses that are out of date. Because the cotact lenses are much easier to be infected during long time of use and there is possiblity that the bacterial stay on the surface of the lenses so as to cause eye diseases.
You shouldn't wear annual contact lenses for more than one year because it has an expiry date. If the contact lens is beyond the limit time, the saline solution and lens inside will be contaminated. So you should have an annual eye exam to make sure your eyes are still healthy.