Circuits, methods, and apparatus for storing application data, keys, authorization codes, or other information in a volatile memory on an FPGA. To prevent erasure of the stored information when power to the FPGA is removed, or when the FPGA is configured, or when applications are installed, a battery powers the memory. The battery power may be interrupted, for example if a tamper is detected, in order to erase the contents of the memory. Access to data stored in memory may also be limited by using authorization codes or encryption. For example, an application may only be granted access if it provides the correct authorization code. Alternately, an application may encrypt data with a key before it is stored. Only an application with the correct key can make further use of the data.