A good pair of tennis shoes should last between 5 to 10 years however some brands and higher quality tennis shoes may last as long as 15 to 20 years.
Just make sure to keep the tennis shoes clean and store them properly when not wearing them.
I have a 10 year old pair of tennis shoes and they are still in good condition and I wear them nearly everyday except in the summertime.
In the summertime I wear Crocks shoes or my Sandals instead of my tennis shoes.
But as long as you clean the tennis shoes and keep them from getting torn or ripped apart etc the tennis shoes should last a minimum of 5 years but some can last longer.
After 10 years you might want to buy a new pair of tennis shoes anyway.