Burp Suite is an intercepting proxy that is typically used for Web application and API testing. This software can also be useful for other activities such as password spraying and transaction maniuplation while executing other penetration tests. Burp Suite Professional includes functionality not available in the free version of the software.
The license for Burp Suite can be found in LastPass under the Burp Suite Pro entry. Additional details and training resources can be found at https://portswigger.net.