I’m 20, and had a lip lift. I have olive skin. How long until the red pigmentation of the lip lift scar goes away?

Hello bobspleaseSwelling should subside within 1-2 weeks and tightness should diminish within a few months. Mild discomfort may occur but should not hinder day-to-day tasks. The lip will be a little higher than when it settle into position.  The sutures dissolve but are hard to see even immediately after surgery.  I would advice you visit or contact your plastic surgeon about this concern.

Lip lift scars can be white and visible. Hidef protocols can help with visible lip lift scars on the face. I see a lot of these in my office in Beverly Hills. Surgery is often not needed if lasers and HIDEF scar revision techniques are introduced. 
In our office, we combine treatments starting with topical pre-conditioning of the scars with Plato's Scar Serum for hypertrophy and Melarase PM for pigmentation. Fractional RF, laser, and micro fractional RF can help limit scar growth. Kenalog IIT can also help reduce scar thickness. For lip lift scars specifically, I use selective Hyfrecation to reduce scarring. 
Best, 
Dr. Karamanoukian
Realself100 Surgeon

I’d suggest the use of a scar gel like Biocornium or Strataderm.  Scars change significantly over the course of 6-12 months.  You will also need to be sure to protect it from sun exposure.   Be sure to express your concerns to your surgeon. Best of luck to you!