http://www.newsweek.com/moon-may-have-been-habitable-billions-years-ago-what-changed-1041225

The Moon today is barren, inhospitable and lifeless. It has no atmosphere, no magnetic field to block harmful space particles, none of the complex chemistry necessary for life to emerge, and to top everything off, it experiences wild variations in temperature.

However, there may have been two periods billions of years ago when conditions on the lunar surface were sufficient to support simple lifeforms, according to a study published in the journal Astrobiology.