Aha then it is NOT the evaluation license of DataFlex Reports that expired but from the underlying DataFlex product.

DataFlex Reports is build with DataFlex and v6 uses 18.2. Upon installation it checks if there is a client license (or better) for 18.2 installed and if so it uses that installation. If not it installs its own client license. In both cases with software of course. The installation does not check if the installed DataFlex product uses an time limited evaluation license or not so if that expires DataFlex Reports Studio cannot start. De installation of both DataFlex Reports Studio as well as the eval based DataFlex 18.2 product, a reboot and a re-installation of DataFlex Reports 6.x solves the problem. Of course if you want to develop in DataFlex 18.2 the license code for DataFlex should be entered via register.exe instead of the whole deinstallation and installation steps.