Does paying the expiation definitively nullify the oath, or is it renewed by repeated breaking of the oath?

Masturbation is forbidden (haram). The expiation for an oath (kaffarat al-yamin) is feeding ten poor people, or clothing them, or freeing a slave. If one cannot find these, then fasting for three days. If someone fasts three days for the expiation, then later becomes affluent and finds money, the fasting is sufficient, and he is not obligated to revert to feeding. If you return to masturbation without renewing the oath, you are not required to offer expiation.