Hello Izak,
Simple rule of thumb is
- Users who is capable of adhoc report development and uses multiple businessobjects tools will be potential candidate for Named license. All developers and powerusers will be in this category
- Users who tends to use the reports just for viewing and refresh would be Concurrent users. They will not use the system throughout the day instead at specific intervals as on when required. All report viewers and senior management executives belongs to this group.
Also review your sizing recommendation for the concurrent sessions count and distribute your licensing accordingly for effective licence utilization.
Regards
Mani