Hi,
Yes for the NSRP pair you need to first upload the license on the backup followed by the reboot. Once the license gets successfully installed on backup you need to perform the failover. Once the new master takes over the license has to be installed on the new backup device followed the reboot.
With successful installation perform the failback.
Please refer the below KB article to perform the faiilover and failback in the nsrp cluster:
# https://kb.juniper.net/InfoCenter/index?page=content&id=KB5885&smlogin=true&actp=search
Let me know if you have any further queries.
Regards,
Rishi