Is it permissible to hold a small celebration after memorizing Surat Al-Baqarah, and is that considered showing off or an encouragement to memorize?

It is permissible to hold a party or banquet to celebrate the completion of memorizing the Qur'an, if it is an expression of gratitude to Allah and an encouragement for people to memorize it, provided that it is free from extravagance and showing off, and that its organizer does not believe it to be a Sunnah. This is supported by what Umar ibn al-Khattab (may Allah be pleased with him) did when he slaughtered a camel after completing the memorization of Surat al-Baqarah. However, if the intention behind it is ostentation and showing off, then it is forbidden.