What is the ruling on someone who vowed to memorize Surat Al-Kahf upon obtaining a driver's license, but is finding it difficult due to the surah's length and his preoccupation with exams? And is there an alternative solution for his vow?

A person's statement: "He intends to memorize such-and-such a Surah if he gets the license," is not considered a vow unless he intended it as such. A vow has specific pillars and formulas without which it is not valid, such as saying: "I have vowed such-and-such," or "It is incumbent upon me for the sake of Allah to do such-and-such." A mere statement without the intention of vowing does not make it a vow. However, if he intended it as a vow, then he must fulfill it. If he did intend it as a vow, then he must memorize Surah Al-Kahf, and it is not a condition that he memorize it in one day.