The menu option 'License Details' is no longer available for Confluence Administrators and in confluence-only instances, that don't have the new User Management enabled, there is no way of counting the licenses granted and how many are available.

Affecting Version 5.5-OD-22-001

Workaround:
a) To see how many users are Enabled, count the users in the 'users' group that aren't disabled.
b) If you have a rather large instance, open a support request at http://support.atlassian.com (pointing to this bug) and the OnDemand Support team will provide the result for:

select count(*) as Active from cwd_user where active = 'T';