As Google's algorithms constantly change, I understand that keeping up to date is critical, so I recently successfully completed and gained accreditation for the Analytics qualification. It covers basic and advanced Google Analytics concepts. This includes planning and principles; implementation and data collection; configuration and administration; conversion and attribution; and reports, metrics, and dimensions.
I have also recently passed a PPC course too, as it's another marketing tool many businesses use. The certification answers advanced concepts, including best practices for creating, managing and optimising Display campaigns.