I’ll buy a car from you and agree to pay you $1,000 a month for 10 months. After I take possession, I’ll exercise my right as a free person to refuse further payment. After all, I’ll just choose to end my business dealings with you. What right to complain do you have, since you believe that is OK?
On the other hand, let's say I rent a hotel room from you. Once inside, I break all the windows out, throw all the furniture out the window, and start screaming obscenities at everyone walking by.
In your world, since I paid for my room, I'm good to go until 10am checkout.