[ThePhenix]

You could do this:

pawn Код:

new HasStartedC[MAX_PLAYERS];//global variable 

CMD:startcareer(playerid, params[])
{
    if(HasStartedC[playerid] == 0)//Checks if player has not started a career yet.
    {
        //do some stuff
        HasStartedC[playerid] = 1;//Set the variable for the playerid to 1
    }
    else//If player already started a career
    {
        SendClientMessage(playerid, -1, "Tutorial already used or something");
    }
    return 1;
}