Does showing off invalidate the deed of one who memorized half of the Quran for the praise of people, then repented and sought forgiveness, and should he complete his memorization or not?

Hypocrisy (Riya') nullifies the reward, whether it occurs at the beginning of the action or during it. However, if it occurs after completing the act of worship, it does not harm it. A person's joy in performing an act of obedience or in people's praise does not cause harm if he remains sincere; rather, it is a sign of his faith and Allah's love for him. A Muslim must beware of hypocrisy and the devil's traps, which may cause him to doubt his intention. He who repents and seeks forgiveness for hypocrisy has done well, for repentance erases what came before it. He should continue his good deeds with sincerity and not abandon them for fear of hypocrisy, for abandoning good deeds for the sake of people is hypocrisy. The cure for hypocrisy is through supplication: "O Allah, I seek refuge in You from associating partners with You knowingly, and I seek Your forgiveness for what I do unknowingly."