please be bear with me for this stuipid question. thank you!

I am trying to fill the vehicle registration cancellment form for state maryland. And it asks me about the tag number and sticker number. I know the tag number is car plate number, but not sure about the sticker number (I am pretty sure it is not VIN nubmer). So where could I find the sticker number in my license plate? Thank you very much for your help in advance!