How long does FUE Hair Transplant last?

In theory, hair transplant is meant to be a permanent solutions to the problem of baldness and thinning hair. Even in some specific cases, if it doesn't last a lifetime, it is extremely long lasting and one of the most successful treatments to regain lost hair.
The transplanted hair follows the behaviour of the donor area and will continue to grow as it did in the donor area.
No two cases are the same, so comparing yourself to another before / after picture on the internet and imagining an expected result based on a Google search is not the right approach. Ideally, you should look for a well experienced and qualified surgeon in your city and visit him / her for a consultation.
This is because, permanence of hair transplant is something that depends a lot on suitable candidacy and your surgeon setting the right expectations. Your cosmetic surgeon should be able to evaluate your suitability based on your age, genetics, health record and family history. It is then that the surgeon and patient mutually set the right expectations.

FUE Transplant Results are permanent and as long as the grafts are carefully selected from the permanent zone they won't be affected by male patterned baldness process.  Occasionally patients may see thinning even on their donor area with advanced age.  In those cases transplanted hair may follow the same thinning, but it won't happen in every one.