If you do no show up at the hotel, you should expect the hotel to treat you as a "no show" and keep your money and not credit you the night or points. If PLT is important to you you should at least check-in in person, go up to the room, mess up the bed covers, leave the key on the desk and walk out. If you want to call the front desk the next morning to tell them you have checked out that could potentially free up the room earlier for the next guest.