[Jacapo]

Just create a variable.
For example:

pawn Код:

new IsSpawnedFirstTime[MAX_PLAYERS];

public OnPlayerConnect(playerid)
{
    IsSpawnedFirstTime[playerid] = 0;
    return 1;
}

public OnPlayerSpawn(playerid)
{
    if(IsSpawnedFirstTime[playerid] == 0)
    {
        IsSpawnedFirstTime[playerid] = 1;
        ShowPlayerDialog(playerid,DIALOG_SKILL,DIALOG_STYLE_LIST,"Select your skill","Assault - Free\nSniper - 150 score\nEngineer - 300 score\nPilot - 550 score\nGunner - 700 score","Ok","");
    }
    return 1;
}