The main German word for “reward” is “Belohnung” (f.), and “to reward” is “belohnen”. Specifically for “finder’s reward”, the word is “Finderlohn” (m.) from “Lohn” (m.), which means “wage” or “payment”. A “reward system” is “Anreizsystem” (n.) from “Anreiz” (m.), meaning “incentive”. An older word for “to reward” is “vergelten”.

Examples:
– “Ich möchte dich für deine gute Arbeit belohnen.” – “I want to reward you for your good work.”
– “Ich habe die Katze gefunden und erwarte Finderlohn.” – “I found the cat and expect a finder’s reward.”

The word for “rewarding” is “lohnend” or “lohnenswert” (“worthwhile” or “lucrative”) and “dankbar” in the sense of “thankful”. Note that there’s no great way to translate a “rewarding experience”, though “ein lohnendes Erlebnis” or “eine lohnende Erfahrung” come close.