The Demonic mind's ability to remember "favors" is incredible. There is technically no currency in the Demonic planes, only favors owed, endlessly cycling up and up till all favors inevitably end up in the hands of the seven Masters. If a demon wishes to receive a sword from a smith, they will owe the smith a favor of equal size. But since almost all demons serve a greater master, in truth it is the Master that will either provide the sword, or owe that favor. In return it will be repaid with food, items, services, or perhaps the favors will amass until they can be used for a much larger action.
All is accounted for, and if a Demon Master wishes to call in favors owed, they can mobilize troops, have great treasures created, or even call for the death of someone who has displeased them. Favors are everything, and to truly be "out of favor" is to be condemned to the lowest rungs of society. If no one owes you anything, and you have nothing to offer, then it is not long before you wither and vanish from relevance forever.
There is no charity, there is no care, there is no love for those who have fallen.
Perhaps it is in this way that Demon Society has grown so strong. The weak descend, and the strong rise.
-Musings of the Highest of Angels