How can one review what has been memorized of the Quran and Hadith so as not to forget it, with the review time increasing as the memorized material increases?

You should seek knowledge according to your ability using available means, and the explanations of 'Allamah Ibn 'Uthaymeen are preferred. To memorize the Sunnah (definition), start with An-Nawawi's Forty Hadith (definition) and its continuation, then 'Umdat al-Ahkam, then Bulugh al-Maram, while also looking into Riyadh as-Salihin and the recorded books of Sunnah. Allocate a fixed time for memorization and revision, and be diligent in maintaining even a small amount. Prioritize memorizing the Quran first if you have not already done so, and consult books of Tafsir (definition) such as Tafsir al-Sa'di and Ibn Kathir. Organize your time and seek Allah's help so that He may grant you beneficial knowledge.