I don't think it is acceptable to abbreviate the word memoir. In general I am opposed to abbreviations with some exceptions. If you are conducting classes, are a participant of a forum, etcetera, and everyone knows what the abbreviations mean, it would be alright. If you are not writing to an informative group of individuals it is customary to spell out the full word or group of words followed by the abbreviated form in parenthesis. In the rest of the article you may use the abbreviation. Consider someone who is searching the web for an answer to their query and they come across an article that addresses their query. The article is full of abbreviations and acronyms and the full reference to the abbreviations or acronyms, if there are any, are buried in the article, (the full reference to the abbreviation or acronym will only be cited when the author starts to use them.) The reader quickly gives up and leaves the website because of time constraints. In this instance the abbreviations and acronyms take a hundred times or more to research what they mean and stand for, while the intended purpose for abbreviating and using acronyms is to save time. Are we sure we are trying to save time, or are we just lazy?