You can also activate your product from the main menu under Help > Manage license or Protection status > Activate product.
To activate your copy of ESET Endpoint Security for macOS directly from the program, click the ESET Endpoint Security for macOS icon ( ) located in the macOS menu bar (top of the screen) and click Product activation. The availability of a particular activation method may vary depending on the country and the means of distribution (CD/DVD, ESET web page, and so on) for your product. After the installation is complete, you are prompted to activate your product.