Devart has a virtual in memory table component for Delphi XE5 Firemonkey that works on IOS and Android. The component is called TVirtualTable and is a descendant of TDataSet. It supports both LoadFromFile and SaveToFile so not only is it an in memory table dataset but you can also store the contents as a file (or even a stream). You can also define fields in a table at design time and deploy them in your project. The component supports ftString, ftWideString, ftSmallint, ftInteger, ftAutoInc, ftWord, ftBoolean, ftLargeint, ftFloat, ftCurrency, ftDate, ftTime, ftDateTime, ftBlob, and ftMemo field types. The component is a commercial component but it appears that you can use it for free without source code. If you want source you can purchase a license. This component seems similar to the FireDAC SQLite components which have an in memory database option.
Head over and download your free version of the virtual table.