Bonjour!
1) In my opinion, how you feel at the moment is what makes a memory unforgettable. You will think of that memory and will have a bit of that sensation that you had the moment that memory was taken. A memory is made when you are feeling overwhelmed with what you see, hear, smell, think...
2) You remember something for the rest of your life when that thing has impacted you, positively or negatively, physically or mentally.
3) Memories are pieces of your life, they are why you’re here now and why you are like you are. They are important.
Voila quelques idees j’espère que ça t’aidera :)