You can also check the withdrawal limit of a user from the GetBalance response by checking callback.withdrawalLimit. 
ZBDController.Instance.GetBalance(callback=>
{
  if (callback.success)
  { 
    // the users withdrawal limit in satoshis (not millisatoshis)
    Debug.Log(callback.withdrawalLimit);
  }
  else
  {
    Debug.LogError("get balance error " + callback.message);
  }
});