I lost 100 lbs but still have belly flab. i exercise 3-5 times per week. will the flab ever come off if i keep working out or will i have it for life?

If you mean hanging: Skin - that is not likely to respond to exercise. Plastic surgery can be considered for excessive skin. Spot fat loss does not occur naturally. By losing weight in general a certain amt will be abdominal fat. Eat healthfully ; be physically active. Calories burned must > calories consumed. To tighten ab's do crunches, reverse crunches, exercise ball crunches, pelvic thrusts ; lying leg raises.