AZ-800 Study Guide: Administering Windows Server Hybrid Core Infrastructure

You have - renewal is a relatively painless and quick process. You are given a list of modules to review on learn.microsoft.com and then a short test (you can take the test right away if you want). The test is also "open book" unlike an exam so you can try to research your own answer if you have enough time. Pass the test and you are renewed for the next 12 months. Fail the test and you can take it again the next day and the next and the next until the renewal date (which is why you don't leave it to the last minute). If you go through the list of modules you'll discover that what you are tested on is covered somewhere in the modules. 

When renewing and you're going through the test and you hit something you don't know - make a note of what is being asked.  If you don't pass the test then you can go follow up on that topic and then come back the next day knowing more than you did and having a better chance of passing.