What is the ruling on writing memoirs on special memory books?

All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.

Writing memoirs on special memory books is not a Muslim tradition but a tradition of the polytheists which was imitated by irreligious Muslims.

Rather, we are commanded to be different from the polytheists in everything, including their religion, feasts, clothes, customs, traditions etc., pursuant to several Sharee‘ah (Islamic Legislation) texts. 

Ibn Taymiyyah of the Hanbali School stated many evidences on the prohibition of imitating the non-Muslims, among which are the following:

1-   Allaah Says (what means): {And never will the Jews or the Christians approve of you until you follow their religion. Say, "Indeed, the guidance of Allah is the [only] guidance." If you were to follow their desires after what has come to you of knowledge, you would have against Allah no protector or helper.}[Quran 2:120]

2-   It was narrated on the authority of Abdullaah ibn ‘Umar that the Prophet, sallallaahu ‘alayhi wa sallam, forbade us from imitating the non-Muslims and mentioned that whoever imitates them is one of them. [Abu Ya‘laa] 

Thus, it becomes clear that buying and exchanging such memory books and autographs is prohibited.

Allaah Knows best.