What is the maximum amount of data that can be stored using JSON on dR in one user account ?

Thanks for the answer. Sorry for being late.
Basically game data generated by the user, which I already have in binary format and need to store somewhere. This game data is used by (the 2) friends sharing the same game. It rests in one user account and is used by each friend, turn-based style. This is really the last stumbling block I have on the dR side before starting my public alpha.