I have had my Olfa mats for 30+ years and they are still working well. One of the ways that destroys your mat (other than heat) is not cutting your fabric perpendicular to the mat. In other words, your cutting blade should be used straight up and down and not sideways. A lot of people use their rotary cutters on a angle. When you make a lot of cuts, eventually you will get nicks in the mat and that destroys the mat. When your mat is 'self-healing' it closes up the cut you have just made into the mat. But if you cut on an angle and later cut over that same cut straight up and down, you have just made a divot in your mat. After years of cutting on your mat making divots, your mat will no longer be able to self-heal.
Another thing about keeping your mats in good condition is not to store your mat by a window. The heat coming from the window, or direct sunshine on the mat, will not only warp the mat over time, but also dry the mat out making it brittle.
As I recall, if you go to Olfa's website, they have directions on keeping your mat in good condition.
One more thing, I keep an Olfa mat in my car's trunk at all times. I go to the senior center to sew every week and I think that it is a hassle to take it in and out of my car each week. I keep the mat in good shape by putting a thin piece of plywood (the same size as the mat) above and below the mat. Then I clamp the boards together with those big black binder clips on all four sides. Even in the heat of the trunk my mat doesn't warp and I have had the same cutting board for years doing it this way.