Yes, it is compatible and will provide licenses to previous ArcFM versions. Here is a Knowledge Base document that explains this: FAQ - ArcFM - ArcFM License Manager 10.2.1b Installation and Compatibility.
As Kevin explained there is no problem with having the most current ArcFM License Manager installed when using older ArcFM versions and/or ArcFM licenses. Did you have any other questions on this? If not please mark the discussion as Answered. Thanks!
- Terri Harris, ArcFM Support