Issue
The Subscription Report button not available in Central Administration > Nintex Administration > Licensing
Resolution
Contact the licensing team and ask them to provide the correct subscription license
Additional Information
This feature is not available in Nintex Workflow 2010 and 2013
Below is a link to the help file on how to access the report
https://help.nintex.com/en-US/nintex2016/current/sp2016/Workflow/NWAdministration/SubscriptionReport.htm