Yes, you can. To activate the software you need a license file suitable for "offline" environments. You must contact our Sales Team to obtain a offline format for the Enterprise software you wish to use. 

You can read about this in more detail in the following articles: 

How do NoMachine server licenses work in v9 
https://kb.nomachine.com/AR10U01206

Purchasing a new subscription from the store provides you with license files that are validated through the NoMachine licensing server. You must ensure that outbound access on port 443 (HTTPS) is available. The license file is installed once on the server machine which is then  You can read more about online licenses and what is required in the following article:  https://kb.nomachine.com/AR11U01209