If I'm staying in a Vegas hotel and the check-in age is 21 do I still have to show my ID at that hotel's bars?

My boyfriend and I will be staying at the Stratosphere in Las Vegas this coming weekend and our friend is gifting us with one of his free compensation rooms, so we'll be staying under his name. I'm 20 and my boyfriend's 19, but the person who got us the room is over 21, so he'll be checking us in. Since we're going to be there over the 4th of July, we wanted to participate in some of the festivities the hotel is having (which includes cheap drinks). Basically, I was wondering if they'll still check my ID if we go to buy drinks at the hotel, even though the check-in age to stay at the hotel is 21? Please let me know :)