Whenever fat grafting is performed, the area that receives the fat will be swollen and will have many fat cells in it for the first couple of weeks that will probably not survive. In most cases, the swelling and fat cells which didn't survive will be totally gone by about 2-3 months....
It is still too early to be concerned about a lump in your lip after fat grafting. It could still be swollen for several more weeks. You could also have a small hematoma or collection of blood under the lip skin. I usually recommend light massage of the lips to soften a lump...
The survival of grafted fat is variable from procedure to procedure. As it is essentially impossible to quantify the survival of grafted fat as a percentage of the total amount of fat that was transferred, I instead tend to look at it in terms of what percentage of the overall improvement...