Visit LemonSqueezy.com and sign in to your account. As a Totals user, you'll be able to track your Lemon Squeezy revenue directly from your Mac's menu bar.
Navigate to "Settings > API" in the main menu. Click the "+" button to create a new API key. Enter "Totals Integration" as the key name and select a future expiration date.
Copy your newly generated API key and paste it into the Totals macOS app when prompted. Your Lemon Squeezy revenue data will begin syncing automatically, giving you a convenient overview right from your Mac's top bar.