I developed black spots in my face after facelift. (Photo)

Based on your photos, you have compromised areas of skin were the flap was elevated. I am not sure how long ago was your facelift surgery. If it was more than 2 weeks ago. This discoloration will not turn to worse  to become necrosis. This can happen occasionally after face lift surgery, more commonly in smokers. This usually heal well - just continue to follow up with your surgeon for postoperative care.  

Based on your photo it looks like you may have compromised blood flow to the skin, and at best severe bruising. It is very important to followup with your surgeon to see if you have a hematoma or any other actionable cause of this discoloration. Always make sure you surgeon is experienced and board certified, for example the American Board of Plastic Surgery. You need to see your surgeon as soon as possible.

You have two dilemmas one is the healing and colour of your face and the other is the follow up care of your surgeon.
Your face around the ear appears to be dark and dusky which indicates that the skin flap has a compromised blood supply and is struggling. This can happen during a facelift and worse case scenario the skin blood supply fails and the skin slowly sheds and heals over 3-6 weeks. Normally what happens is the skin recovers slowly and is just slower to heal. There is not much you can do with regards to the healing of the skin and its colour, except stop smoking if you are a smoker.
Your surgeon should see you to examine the skin and talk you through what is likely to happen as he/she best knows your medical condition during and after surgery. I am sure if you were to send this photo to your surgeon it would prompt him to see you ASAP. If not i would see another plastic surgeon.