Thanks guys. I already found my own answer and here it is in case someone wanted it:
The upgrade path is 4.1 > 5.0 > 5.0.2 > 5.1 > 5.2
However DMP 4300G supports only up to 5.1 so I will stop there.
Regarding the license, it does migrate automatically provided that it is installed properly before the upgrade process is started.
BR