Every TFS admin knows about the Operational Intelligence page. It is a very important tool for managing Team Foundation Server, which provides lots of useful information about service usage.
Nothing like that existed for VSTS, up until a few sprints ago. Now if you look at the Account level settings…
The Usage tab is a revamped version of Operational Intelligence for VSTS! Of course you won’t be interested in the server-side jobs as it is a service, but here you can get all the usage audit about a certain user:
It is worth noting that there are rate limits (the Usage column, expressed in Team Services Throughput Units), so you can be throttled or stopped if you are exceeding these – usually with an automated tool or a script. More about this here.