First of all, never memorize answers and then use them on the test. These are not your ideas- they don’t reflect your life, your experience, your country, or your culture.
Thus, they are not natural or ‘appropriate’, which your answers must be if you want a 7+ on IELTS Speaking. If you use answers that aren’t yours, it will directly affect your Fluency and Coherence, Vocabulary and Pronunciation scores. You can, however, use other people’s sample answers to learn the variety of ideas and examples that are possible to give on the Exam.
You can also pick up new and interesting vocabulary, and mimic natives to improve your pronunciation. In short, learn FROM sample answers, but do not memorize them.