Of course you may remove the license codes and restart NW. This will work - at 
least for very old versions (6.x).

To the best of my knowledge, NW also saves at least the base enabler in the 
media index. And this means that this method will not work for too long (i 
guess one day).
Yes, you may start all over (deleting the /nsr/res, /nsr/mm & /nsr/index 
directories) but then you will loose all configuration and backups.

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