Customers who upgrade to Chef Server 12 may notice the following message displayed at the top of the Chef Manage console:
This installation is managing 26 nodes, but is only licensed for 25. Please upgrade now to ensure proper licensing.
Chef Server 12 does not take or use license keys. The Chef Server core will not limit nodes functionality in any way. The Chef Manage interface will only provide a "nag message" if your node count exceeds a certain value (25 by default).
Licensed customers are recommended to change that value by setting the following attribute in the /etc/opscode/chef-server.rb file:
license['nodes'] = NUM_LICENSED_NODES
Where NUM_LICENSED_NODES is an integer value that matches your Chef Premium Subscription node count.
Then, perform a chef-server-ctl reconfigure and chef-manage-ctl reconfigure for the setting to take effect. In Tiered and HA Chef Server topologies, these steps must be performed on all of the Chef servers.