In order to stock the consuite and green room at an affordable price, a concom will often seek a corkage waiver in order to bring in outside comestibles and drinks instead of buying catering from the hotel. This is an agreement by the facility that it will waive (for free or for a flat fee) its usual right to sell all food or beverages or both being dispensed in its facility.
The term "corkage" comes from the restaurant business, which traditionally charged a fee to remove the cork from wine brought to the restaurant by diners. Today, corkage has become a general term covering food and beverages, though, sometimes you will see the term "forkage" used to apply specifically to food.
A corkage waiver is frequently not general but often applies only to specific parts of the hotel (e.g., specific function rooms) or only to nonalcoholic beverages.
Corkage rules will often differ substantially between sleeping rooms and function rooms, since in many localities hotels are specifically forbidden to control eating and drinking and serving of food and drink in sleeping rooms. Hence, room parties don't need to be covered by the waiver.