CirrostratusHi Subrun,
When nodes are running different versions, you can change role of standby node to active.
For license verification, the BIG-IP and Enterprise Manager systems verify the license check date in the software against the service check date in the license file. If service check date older than license check date, you must reactivate licenses in both nodes.
The license reactivation process may reload the configuration and temporarily interrupt traffic processing.
grep "Service check date" bigip.license