The Billing & Subscription tab should automatically show once you go to your Account and Settings page.
Outdated cache files in your web browser may have caused this missing tab in QuickBooks. I'm here to help you on how to fix this.
First, use an incognito browser to check if you can view this option. Depending on your browser, here's how:
Google Chrome: Ctrl + Shift + N.
Mozilla Firefox: Ctrl + Shift + P.
Internet Explorer: Ctrl + Shift + P.
Safari: Command + Shift + N.
Next, sign in to QuickBooks using this browser and go to the Gear Icon. Select Account and Settings and check from there if you can view the Billing & Subscription tab. If it works, you can go back to your regular browser and perform the troubleshooting steps provided in this link: How do I clear my browser cache and temporary Internet files?