If you’ve been running a Trial version of ESET then this how to complete the set up.
LICENSING
Locate the ESET icon in the tray (bottom right) and double click. ESET will load up.
Click on “Activate Full Product“
(if you don’t see the Activate Full Product button then go to Help & Support then Activate Product)
Click Use a Purchased Licence Key
Enter or paste the product key and click Continue