I see this is an old thread, but I also have something to add for future finders on this topic. In addition to having an individual key for the months as well as a unique name, you could have a composite key identifying the month and year and use only the month name. In this case the names would certainly be non-unique as Month 1 Year 1 would have the same name as Month 1 Year 2.

Also agree with the comment about you may still want a different attribute where January is Month 1 so that Januarys can be compared more easily. I would think in this case the member name would be unique because there would only be 12 members.