If you're referring to your QuickBooks Desktop license number, you can log in to https://camps.intuit.com/ or you can open your QuickBooks and press F2 on your keyboard. This will show information about your product including the product number.
This information can also be accessed by clicking the Help tab at the top of the page, then choose About QuickBooks.
Additionally, if you purchased QuickBooks in a physical retail location, the license number will be listed on the packaging. If you purchased your product online, the license number will be included in the confirmation email.
Keep me posted with the results. I'm always here if you need further help. Have a great day!