I don't know how long it will last but I am pretty sure that you need to keep it clean and dry between uses. I used to keep mine under my reef tank and I had to send it back to the supplier twice for repair. I now keep it in a drawer away from the tank and any contamination. Every time I use it I finish by washing the probe in RO and drying it before storing it away in the drawer. Since doing this I have had no problems in about a year so far.