Abstract: A single use reminder device (100) has a tamperproof housing which contains a counter circuit and a power supply. The device includes a status indicator (106) for indicating when a date or time period has elapsed. The device also includes a button (104) can be depressed so as to activate the status indicator (106). A traffic light LED system is operated, whereby a red signal is shown by the status indicator (106) if the date or time has elapsed, and whereby an amber signal is shown if the elapse date or time is imminent. A similar device comprises a laminated card structure having a portion, which can be pressed to provide status information via an LCD.