https://support.eset.com/kb3431

1. Open a new Terminal window by clicking Applications → Accessories → Terminal.

Figure 1-1

2. Type the following commands in the order shown below and press Enter after each command. Enter your password when prompted (the cursor will not move as you type).
   
   
   1. cd /etc/opt/eset/esets/license
       
   2. sudo rm esets_*.lic


   3. cd /opt/eset/esets/sbin

Figure 1-2
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3.  To verify that you have successfully removed your expired license, type the command shown below to restart the ESET service. You will receive the error notification Cannot initialize scanner: License not found, repeat step 2 if you do not receive this error.
   
   sudo service esets restart

Figure 1-3
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4. Type the command below to import your new license file. If you saved your new license file to your Desktop, the location of new license file will be similar to /home/eset/Desktop/EFSW.lic (see Figure 1-4).
   
   sudo./esets_lic--import location of new license file (for example /home/eset/Desktop/EFSW.lic)

Figure 1-4
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5. Type the command below to restart the ESET service again. When you receive the notification OK, your new license has been imported successfully.
   
   sudo service esets restart

Figure 1-5
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