You can only restore on the same version. So if you take a backup of a 17.3.1 repository, it can only be restored on a 17.3.1 instance.
When moving from one machine to another, make sure they are both on the same version of NPrinting. Once the backup is restored on the destination machine, take a backup (in case something goes wrong with your upgrade) and upgrade the destination instance to the new version. Same is true if upgrading on the same machine. Please read the release notes carefully as there is an upgrade path to be followed. Although there should be no problem for you to upgrade directly to June 2007 or September 2017 as you are on 17.3.1.
HTH - Daniel.