Can one repent of spending lawful money on unlawful things, or is regret of no avail?

Repentance is beneficial for every sin if it is sincere (nasuh) and performed at its legally accepted time. The one who repents becomes as if they had not sinned. The path to repentance is open and never closes. A Muslim must abandon the sin, regret it, and resolve not to return to it. One should trust in Allah's forgiveness and generosity, increase in good deeds that expiate sins, adhere to acts of obedience and remembrances (adhkar), and keep company with the righteous.