The longevity of concrete sealers is dependent on a number of factors. First being the type of concrete sealer, meaning its composition – acrylic, epoxy, urethane, silicate. On average acrylic sealers tend to need reapplication within a year or two of being applied. Since they are topical sealers adhering to the concrete they are prone to traffic which causes flaking, peeling and bubbling. There are some excellent acrylics out there, mainly water based acrylics, that will last up to 5 years before needing to be re-applied. Since water based versions do not leave a high gloss shine there is less risk of the aforementioned issues. Solvent based acrylics may peel, flake and decomposed quicker at signs of UV rays and traffic.
Epoxies and urethanes if applied to a clean surface with a good surface porosity (using an epoxy primer and urethane top coat) will adhere and last up to 10 years. Silicates on the other hand are penetrating densifiers which have no risk of peeling, flaking or bubbling. Through a chemical reaction they form a denser, harder, stronger slab which is why many companies offer lifetime warranties on these products. If your concrete is at no risk for water issues and you use a silicate densifier to seal the concrete you should not need to reapply or seal it.
Our Take: Look for companies like Kretetek and Stone Technologies, offering warranties on their products so you will be covered if their products do not live up to their claims.