The image below is a schematic flow diagram of a typical oil refinery that depicts the various unit processes and the flow of intermediate product streams that occurs between the inlet crude oil feedstock and the final end products.
In order to check-in into a hotel, the person must be 21 years old.  If the person is younger than 21, then a parent or guardian can  give permission for them to check-in. 1 person found this useful.
The simple answer is yes, most hotels run the Front Office 24 hours and if they have a room available to suit your needs and theirs they will check you in. However, most hotels have posted check-in (~3-4pm) and check-out (~11-12pm) times. If they don't have a clean room they are under no obligation until check-in time.