The plug-in Bad Elf GPS can only maintain power and hence a lock on satellites if it is being used by an app.  If no app is using it, your iOS device will power down your plug-in Bad Elf GPS within ten seconds.  The “Background Tracking" feature will keep your plug-In Bad Elf GPS powered and locked on to satellites even when our app is running in the background.

This setting is found under App Settings beneath the Plug-In GPS subsection