The EDS-safe properties don’t fade over time. The only thing they have to worry about is wear-and-tear on the surface. If a walking surface, I would recommend a floor coating instead. If a working surface, I would suggest putting and ESD-safe mat over the Licron Crystal coated surface. Licron Crystal is not chemically resistant, so the mat becomes very important if we are cleaning with a solvent like IPA and dripping it all over the place.
If it is a surface out of reach, so it doesn’t get abused, I would recommend they check the resistivity every month, if it is critical, or every 3 months if less critical. If the resistivity hasn’t changed, they can leave it alone. How often they will have to reapply depends on the environment. If a clean environment, they can wipe down with water and make it last for a very long time – years even. If in a greasy, sooty environment, they will have to clean with some kind of cleaning agent, which can degrade the coating. This will require more frequent reapplication.