The unified auditing functionality in Microsoft 365 provides organizations with visibility into many types of audited activities across many different services in Microsoft 365. Advanced Audit helps organizations to conduct forensic and compliance investigations by increasing audit log retention required to conduct an investigation, providing access to crucial events that help determine scope of compromise, and faster access to Office 365 Management Activity API.
It is not so expensive in comparison with other products, but I can tell you about an example.
I'm not aware of the pricing of licensing terms.