I lost my hard drive and had to go back to 2008 to retrieve some state returns that are still in litigation.  I was able to download 2015 without any problem, but that wasn't the case with some of the earlier years.  I actually had to find the old laptop that had those early programs on them and bring the files up with the old computer in the early years.  For 2015, I don't specifically recall what I did, but I notice that under File there is a tab for 'RETRIEVE' and a tab for COPY product license.  I wonder if that isn't the fast path license and whether you can copy that from 2014 and somehow paste it into 2015 to make it operative.  ProSeries Support is atrocious on these prior years.  With the five year carryback, there is absolutely no excuse for them to not offer support for those years.