How to Initialize other WP8.1 xaml?

I have a login screen, and i am inserting a flag with SQLite, for example.

conn.CreateTableAsync<logon>();
if (data[0].findmember.ToString() == "1")
{
    logon log = new logon();
    log.log = 1; // get flag
    await conn.InsertAsync(log); // insert flag
    Frame.Navigate(typeof(Home)); // change xaml page
}

> i need get the flag value, because, i need to change automatically in the next time

public MainPage()
{
    if (sqlite.table == 1 ) //example
    {
      Frame.Navigate(typeof(Home));
    }
    else //login page
    {
    this.InitializeComponent();
    this.NavigationCacheMode = NavigationCacheMode.Required;
    numInput();
    }
}

I need to show the login screen only 1 time