Short reckonings make long friends.

Meaning: Settling debts promptly prevents resentment from festering and eroding relationships over time.

Origin: Settling accounts promptly keeps friendships free of resentment. A book of 1530 already quotes "the common proverb" that often reckoning holds long fellowship.

Equivalents in French, Spanish, German, Italian, Portuguese, and 2 more languages

French: Les bons comptes font les bons amis (literally: Short reckonings make long friends)
Spanish: Cuentas claras, amistades largas. (literally: Clear accounts, long friendships.)
German: Kurze Rechnung, lange Freundschaft (literally: Short reckoning, long friendship)
Italian: Patti chiari, amicizia lunga (literally: Clear deals, long friendship)
Portuguese: As boas contas fazem os bons amigos (literally: Good accounts make good friends)
Dutch: Effen rekeningen maken goede vrienden (literally: Settled accounts make good friends)
Russian: Счёт дружбы не портит (Schyot druzhby ne portit) (literally: Keeping accounts doesn't spoil friendship)