Nanoelectromechanical relays are inherently radiation hard and can operate at high temperatures. Thus, they have potential to serve as the building blocks in non-volatile memory that can be used in harsh environments with zero standby power. However, a reprogrammable memory cell built entirely from relays that can be operated with a digital protocol has not yet been demonstrated. Here, we demonstrate a fully mechanical digital non-volatile memory cell built from in-plane silicon nanoelectromechanical relays; a 7-terminal bistable relay utilizes surface adhesion forces to store binary data without consuming any energy, while 3-terminal relays are used for read and write access without the need for CMOS. We have optimized the designs to prevent collapse to the substrate under actuation and recorded voltages of 13, 13.2 and 27V for programming, read and reprogramming operations. This non-volatile memory cell can potentially be used to build embedded memories for edge applications that have stringent temperature, radiation and energy constraints.