> A memoir (/ˈmɛm.wɑːr/; from French mémoire [me.mwaʁ], from Latin memoria 'memory, remembrance') is any nonfiction narrative writing based on the author's personal memories. The assertions made in the work are thus understood to be factual.

Any work of nonfiction will end up with some inaccuracies and a form based on one person's memories may be especially prone to this. But if he's outright deliberately fictionalizing events (not saying he is, necessarily), that's a big mark against the work. I mean that's exactly what got James Frey castigated on TV and made persona non grata.