If the server running the SolidNetWork License Manager is not connected to the internet then the software can be activated manually through email.
Here are the steps to activate a SOLIDWORKS Network License manually using e-mail:
Step 1: Launch the SolidNetwork License Manager and on the Server Administration tab, click the Modify button.
Step 2: Select Activate/Reactivate a software license and click Next >
Step 3: If a firewall is in place make sure that the option is checked and the proper port numbers are entered in, then click Next >.
Step 4: Select the option to activate Manually via e-mail, then click Next >.
Step 5: On the Manual Activation screen, click on the Save… button.
Step 6: Save out the activation request txt file and transfer the file to a system with an internet connection.
Step 7: Email the file to firstname.lastname@example.org. Leave the subject field and email body blank to avoid any delays in receiving the activation response.
Step 8: The activation response email should be received within a few minutes of the activation request being sent. Transfer the response .txt file to the server computer.
Step 9: On the Manual Activation screen, click Open… and select the activation response file then click Open.
Step 10: Once the activation successfully completes click “Finish”. If the activation does not complete successfully, contact your SOLIDWORKS VAR for further assistance.
Here is video for the steps described above