[Jarnu]

Create a variable

pawn Код:

new IsPlayerInDM[MAX_PLAYERS];

Then add the following

pawn Код:

if(IsPlayerInDM[playerid] == 1) return SendClientMessage(playerid, 0xFF0000FF,"/exit before you use this command");

now /exit command

pawn Код:

CMD:exit(playerid, params[])
{
IsPlayerInDM[playerid] = 0;
SpawnPlayer(playerid);
return 1;
}

and under your DM command add

IsPlayerInDM[playerid] = 1;

+REP if it helped.