Log in to your LeadOwl account from the desktop/web app version.
Click on Account from the side navigation.
Click on Settings.
From the Subscription Settings area, click on the Update Plan button at the top of the page.
A popup will appear showing your current Solo plans options. Since you're wanting to upgrade to an Agency account, click on Check Out Agency Plans here.
A popup will appear with the two Agency Plans to choose from.
Click on the button for the Agency monthly or annual plan you'd like to upgrade to. You'll be prompted to confirm the purchase, and your card on file will be billed immediately to upgrade your plan.