have you already upgraded to 8.3 or do you want to?
since 8.3 is only available for cDOT and not for 7-Mode.
If you currently have a 7-Mode system and you want to upgrade to 8.3 you need to migrate to clustered Ontap first.
This is not like a default upgrade - your data must be off the filer and the filer must be reset to factory default and switched to boot_clustered within "bios" - after re-setup your filer in cDot you then can move back your data use cDot as your filer's OS.
does this need additional licenses? yes, clustered Ontap needs a Cluster-License, but you can get this license without a fee - just open a case at support and tell them that you need a cluster license because your about to switch to clustered ontap - they will send you the license and it will also show up in your software licenses within your support-portal account.