When someone gets a kidney transplant if the Kidney comes from a Living donor then the Kidney transplant lasts from 10 to 20 years.
If the Transplanted Kidney came from a deceased donor the Kidney from deceased donor lasts from 8 to 12 years.
So a person is expected to live from 10 to 20 years after a kidney transplant but some people have lived even 30 years or even a normal lifespan after a kidney transplant.