Skin discoloration after laser hair removal, is this permanent? (Photo)

I am sorry you had this problem.  You do have several options for improving the discoloration.  Prescription strength hydroquinone, especially when combined with a small amount of Retin-A, can significantly improve hyperpigmentation.  However, you do have to use it consistently for several months in order to see results.  In addition, you need to be very diligent about using a good sunscreen, because any sun exposure to your legs is going to make the pigment look even darker. You can also consider laser treatments such as IPL or Limelight, which are designed to reduce excess pigment.  Only get your laser treatments where a physician is on site and supervising all providers.

After 3 yrs, and no improvement, a different strategy must be used!  It is unclear from the picture if the problem is that the skin was depigmented or there are areas of hyperpigmentation? You need to see a skin care expert.

I am sorry that this has happened to you, but there are some treatment possibilties to correct the problem.  I do not know your skin type and that will have an effect on the proposed treatment. In your photo you appear to have loss of pigment secondary to the laser but I am not sure if you were tan when treated and if you tan very easily.  But here are some suggestions:
1. See the doctor at the clinic where you were treated.
2. RX: Hydroquinone with tretinoin and triamcinolone
3. Photofacial, IPL or BBL, in the winter when legs are covered, to refine pigment gradually by removing sun damaged skin. 
4. Sun avoidance
A combination of these tools may be used, but do not try to resolve the pigment quickly.  It will improve over time with conservative treatments.