Do you think the abbreviation acceptable?

No. There is no need to abbreviate the word memoir.

NO good.
That is not recognizable.

It is a mistake to speak or to write in abbreviations,
of chopping off part of a word; it looks unacceptably bad.

Abbreviations are used to save time when a word has to be repeated many times. As has been mentioned, this is normally not needed, especially with a word such as memoir.

I suppose that it`s not beyond the realm of possibility that this or any word could be shortened precisely because it is being used a lot. In that case, the abbreviation could be whatever was mutually understandable to the parties concerned.

Still, manuscript is often abbreviated. Doesn't make any more sense than abbreviating memoir.

Even okay is abbreviated, Roger.