Is it like an eternal gift? Do we owe something back?
Does it fall under the laws of entropy and physics in the phenomenal universe, e.g. conservation? Or the psychological laws of ups and downs, highs and withdrawals? Or the laws of living things: being alive or dead, aging, and heredity/genetics?
Is there anything else similar that does not obey the aforementioned laws? If yes, what? If not, how then do we hypothesize that existence is a single transaction-free, owing-nothing substratum beyond laws and logic?
Is there any chance that it can be the opposite and complementary side of nothing? Could nothing itself be the loan taken, ending in nothing? See The surviving branch for the view of existence as the single surviving branch.