Quedar a deber, to still owe part of a debt or an obligation. Estar a mano, to be even, with nothing owed on either side, according to the Diccionario del español de México. Echar una mano, to lend a hand. Hacerle la valona a alguien, to do something for someone out of solidarity or complicity.
People who only take have their own words. A gorrón eats and drinks at the expense of others. A conchudo shamelessly takes advantage of other people’s work. Al nopal sólo se le arriman cuando tiene tunas, “people only come near the cactus when it has fruit.”