Why cellulite treatment creams don’t work in the long term is simple, cellulite is basically fat and you can’t get inside a fat cell with creams and make it dissolve away.  What cellulite treatment creams can do though is temporarily make the skin feel and appear firmer and thus reduce the appearance of cellulite.  Here is what Dr. Oz says on the matter:

There is a massive billion-dollar industry of anti-cellulite treatments, and Dr. Oz says all of the treatments—from creams and balms to procedures like rolling and smacking—have one thing in common: They don’t really work. “You can’t put a cream on and get inside the fat cell,” he says.

While they may be able to give you a short-term reduction in appearance of cellulite—caused by swelling in blood vessels and tissue—”It doesn’t hold,” Dr. Oz says.