Hello Eduard,
I work for NetApp doing consulting projects.
Nearstore option should be left enabled, no need to double check it.
Your licenses will persist after upgrade unless they were expired temporary license keys.
Regarding FlexCache, you would check for FlexCache options at the command line.
For Multistore, you would check for running or stopped vFilers other than "vfiler0".
See this command line example:
ps7mode1> options flexcache
flexcache.access none
flexcache.deleg.high_water 90
flexcache.deleg.low_water 50
flexcache.enable off
flexcache.per_client_stats on
ps7mode1>
ps7mode1> flexcache stats -C
flexcache stats: No statistics were found as requested.
ps7mode1>
ps7mode1>
ps7mode1> vfiler status
vfiler0 running
dmzvf01 running
ps7mode1>
Run those commands on both storage controllers of your HA pair. If you were running clustered Data ONTAP you could query all nodes of the storage cluster from a single shell =).
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Cheers!
Hadrian