But that is the point... you don't have to store it in an underlying browser db. It runs as an in-memory store if you don't use an underlying engine. The persistence module is an optional extra and doesn't even need to be included in the library.
But a DB offers usually persistency and you called your product ForerunnerDB
I still think that the communication/positioning/branding of ForerunnerDB could be improved since it's misleading.