15 Cm Long Scar on my Left Cheek, Best Treatment?

Unfortunately, your scar runs counter to the lines of tension in the face which makes it more visible. One simple potential solution is to purchase Dermablend cream and powder makeup in the appropriate skin tone to camouflage the scar. The photo does not visualize the depth of the scar. It is possible to consider scar revision, preferably serial excision of limited segments to produce a thinner scar but this would involve a healing period and there are no guarantees. There is no such thing as scar removal cream. Once the skin has been breached, there will always be a scar. I also recommend that you avoid sun exposure and use sunscreen religiously.

Begin treatment with a topical skin lightener such as Melarase PM first. The next step would be fractional co2 laser to resurface and even-out the skin. Raffy Karamanoukian, Los Angeles

Creams and lasers will not help this scar after so much time has passed.  While the scar cannot be removed, it can be made less noticeable with multiple small zig-zag incisions to break up the linear aspect of the scar.  I think you could get a very nice result using this technique.