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Fluent License Server

Fluent Designers and Engines licensed with Subscription (modern) licenses need to communicate with the Fluent License Server in order to operate. How often the License Server needs to be contacted depends on the type of license you have purchased.

License Server Hosting and Resiliency

The License Server is globally redundant running on Azure data-centers around the globe in the U.S., Europe and Australia. Communication from your engine or designer is intelligently routed to the best region depending on response time.

It is highly unlikely that all 3 regions would experience an outage at the same time, but if this were to occur or if for some reason your connection to the internet was disabled your Fluent Engines and Designers would continue to operate for a period of time as long as you are using version 21.3.0 or later.

License Buffer Times

PRO Licenses = 168 hours

FLEX Licenses = 72 hours

Note: Perpetual (legacy) licenses and PRO offline licenses do not communicate with a license server

Communication with License Server

The license server requires communication over HTTPS with a minimum TLS version of 1.0 and a maximum version of 1.2

Engines licensed with a PRO License will communicate with the License server every 4 hours for license verification.

Engines licensed with a FLEX License will communicate with the License server prior to processing a template for license verification and after the processing is complete to record the number of pages processed.

Designers contact the License server when office is opened to verify the license and then each time a template is processed (FLEX only) and finally when office is closed.

IP Whitelisting

The Fluent License Server at can take on any of the following IP addresses:

Whitelisting these will ensure communication is allowed with the license server. The port for 443.

Data Communicated to License Server

The license server does not receive Template or Data used in the Template creation. The following is the only information passed to the license server:

  • Your license key
  • Username the Engine or Designer is running under
  • Version of the Engine or Designer
  • MAC addresses for network interfaces on your machine
  • local IP address of the computer hosting the engine or designer
  • Number of pages generated (FLEX only)

Impacts of license server communication on engine performance

Connections to the server happens asynchronously while documents are generating. Even if the connection is running very slowly, it’s going to take longer to generate the document than it takes for us to reach our to our license servers. We also have 3 license servers live in distinct azure regions. Azure Traffic Manager is configured to send requests to the server with the lowest ping time to the location of the machine running the engine.

Troubleshooting Connection Issues

Check that there are no firewall settings preventing communication from the server to the internet.

Test connection to license server: Go to and you will see a status message from the License Server if everything is OK. This does not test your license key, just that your computer can communicate with the License Server and the License Server is running properly.

In some instances the allowed TLS settings on your computer may be preventing communication with the License server. Please read more about troubleshooting TLS here.