The Dose-Alert is intended to serve as a back-up reminder system to help remind you to take your pills. It is not intended to be the sole source for you to remember to take your pills. The Dose-Alert requires you to properly set and activate it. It is battery powered and when the battery runs out it will cease to function.
Like any electronic device, it can cease to function for a variety of reasons, including but not limited to exposure to moisture or to excessive hot or cold temperatures.