Your choice of microcontroller generally determines the amount of flash, RAM, or EE-prom you have to work with. However, you can add external storage for data and files. You can find memory breakout boards for flash chips, SD cards, EE-prom, or even exotic F-RAM storage. They all use standard iSquared-C or SPI comms, so connections are simple and familiar, like adding another sensor to your project. This specific board has 256 kilobytes of pharaohelectric RAM or F-RAM on board, which supports fast reads and writes like common S-RAM, but is also non-volatile, retaining data when on powered, like flash or EE-prom. This makes F-RAM a particularly versatile best-of-both-worlds option for locking data. All it's missing is the capacity and removability of an SD card, but hey, nobody's perfect.