RAGE:MP LifeDb

using GTANetworkAPI;
using LiteDB;

namespace RageFX
{
    class PlayerLogin : Script
    {
        [Command("login")]
        private void OnPlayerLoginAttempt(Client player, string username, string password)
        {

            // player.SetData("loggedIn", 0) set in Main with [ServerEvent(Event.PlayerConnected)] and it works when I e.g. Chat.Output

            if (player.GetData("loggedIn") == 0)
            {
                using (var db = new LiteDatabase(@"./RageCore.db"))
                {
                    var PlayerCollection = db.GetCollection<Player>("players");
                    Player _player = new Player();
                    var Query = PlayerCollection.Find(x => x.Username == username && x.Password == password);

                    if (Query == null)
                    {
                        GTANetworkAPI.NAPI.Chat.SendChatMessageToPlayer(player, "Logged correctly");
                        player.Name = username;
                        player.SetData("loggedIn", 1);
                    }
                    else
                    {
                        GTANetworkAPI.NAPI.Chat.SendChatMessageToPlayer(player, "Wrong username or password");
                    }
                }
            }
            else
            {
                GTANetworkAPI.NAPI.Chat.SendChatMessageToPlayer(player, "You're already logged in");
            }
        }

        [Command("register")]
        private void OnPlayerRegisterAttempt(Client player, string username, string password, string confPassword)
        {

            // player.SetData("loggedIn", 0) set in Main with [ServerEvent(Event.PlayerConnected)] and it works.

            if (player.GetData("loggedIn") == 0)
            {
                using (var db = new LiteDatabase(@"./RageCore.db"))
                {
                    var PlayerCollection = db.GetCollection<Player>("players");
                    Player _player = new Player();

                    var Query = PlayerCollection.Find(x => x.Serial == player.Serial && x.Username == username);

                    if (Query == null)
                    {
                        if (password == confPassword)
                        {
                            _player.Username = username;
                            _player.Password = password;
                            _player.Serial = player.Serial;

                            PlayerCollection.Insert(_player);

                            GTANetworkAPI.NAPI.Chat.SendChatMessageToPlayer(player, "Registred properly");
                        }
                    }
                    else
                    {
                        GTANetworkAPI.NAPI.Chat.SendChatMessageToPlayer(player, "You can't be registered at this moment.");
                    }
                }
            }
            else
            {
                GTANetworkAPI.NAPI.Chat.SendChatMessageToPlayer(player, "You can't register if you're already logged in");
            }
        }
    }
}