The Agents section allows you to specify who is permitted to access the activation system and the keygen. The keygen generates serial numbers and activation codes, so you should not allow everyone to access the keygen URL — only e-commerce providers should have access to it.
The Agents section displays e-commerce providers and other agents allowed to access the keygen. If this is your initial setup, the list will be empty.

By hovering the mouse cursor over a specific row, you can edit the selected agent or delete it. To add a new agent, click the Add New button above, or select Add New Agent in the Agents section on the left.