There are two ways you can access information regarding your purchase and license key on WPDeveloper.
As soon as you make payment for a PRO WordPress Plugin and Theme from our website you will receive an Email receipt. That Email contains all information regarding your account on WPDeveloper, your license key, the amount you were charged for your purchase, validity, and links to our Support and Documentation Page.
In case you can't find your Email Receipt, you can always check information regarding your license key for our WordPress plugin and theme by visiting your account on WPDeveloper. Use this URL to land on your Account Page. https://wpdeveloper.net/account/
You will see five tabs on your My Accounts Page. From the License Tab, you can see a list of the items you have purchased from our Website.
From this tab, you can specify a website for which you are purchasing the plugin. All you need to do is paste the URL of the website. Here is how you can do it.
No matter which WordPress Plugin and Theme you are using from the WPDeveloper team, be it NotificationX or BetterDocs, you can access the license key for all of them from your WPDeveloper Account.
If you face any further difficulties finding your license key, here is a quick Doc on how to seek Support from the WPDeveloper Team.