You can verify QBO plan couple of different ways.
You can easily verify that directly from the Billing and Subscription tab.
From the homepage screen > Click on the Gear (⚙) icon at the top right corner > Your Company > Account and Settings > Billing and Subscription > QuickBooks Plan details.
Another easy way is to check the Gear (⚙) icon panel, look for Budgeting under Tools. If you don’t see any side-up-arrow, it means you’ve PLUS plan. On other plans (Essentials and Simple Start), Budgeting feature is not available and will see side-up-arrow.