Many Kiwi for Gmail plans let you add and manage multiple Gmail accounts at once (up to 9). Each of the connected Accounts does not take up a license or seat that you pay for. Only the first email you log into Kiwi with should find a license.
Consider you have 3 admin emails you want to use in Kiwi: email@example.com, firstname.lastname@example.org, and email@example.com. If you want your license and billing tied to ".com", then when you sign up, purchase, or log into Kiwi for the first time, you will log in with this email first. Once your license is found, you can connect your other Gmail accounts.
Because you can also change the order of your accounts, remember the first one isn't necessarily the one tied to your license! Changing the order doesn't change the license association. You can confirm which email the Kiwi license is associated with by going to Settings > Licensing.