procedure TForm1.ButtonMdaClick(Sender: TObject);
var
  Buffer: array [0..70] of char;
  i: integer;
begin
  for i := 0 to Memo1.Lines.Count do
  begin
    StrLCopy(Buffer, PChar(Memo1.Lines[i]), 70);
    Memo1.Lines[i] := Buffer;
  end;

  while (StrLen(PChar(Memo1.Text)) > 1000) do
     Memo1.Lines.Delete(Memo1.Lines.Count - 1);
end;