The Lunar Laser Ranging (LLR) experiment is now in operation for about fifteen years : has this technique completely achieved its mission? It is here rewieved the technical difficulties to get long series of accurate data necessary for scientific objectives. These ones are listed with particular emphasis of what has been done and what can be improved. Some fields of interest for the future are underlined in the case when a centimetric accuracy will be reached quasi-simultaneously from several stations, well dstributed around the world. These future prospects concern particularly the terrestrial and celestial reference frames, with linkage to other modern techniques, the extension of the resonances in the Earth-Moon system, the tests of relativistic effects, the questions of lunar frictional energy dissipation and the internal structure of the Earth.