i've just brought some this year too. My sister has several plants that have been coming back each summer for a few years now.

They will produce fruit for about three years and, at the same time, produce runners (small plants that grow from the parent plant) pot these up and when the parent plants stop fruiting well your new plants will be ready to fruit. Alternatively if you are growing in the ground you can just leave them and they will grow into full size plants where they are.