Hi,
your H5 license won’t be affected by the trial. The H6 trial will just be placed next it in the eLicenser.
If you are working intensively with customs tags and ratings in the HALion MediaBay, you could backup the mediabay3.db file. After the trial period has ended you should remove HALion 6 from your system and re-install HALion 5 and then copy the mediabay3.db file back in the HALion folder.