Follow the instructions in Setting Up Analytics which consists of these steps:
You can determine that you successfully completed the upgrade by checking the SDK version in Play to Validate step and confirming the correct Editor version (ie: u5.2 or u5.3) is displayed in Validator.
If you did any existing Advanced Integration previously, you will also need to update the namespace and the calls to use the 5.2 and up syntax. Follow 5.2 onwards Advanced Integration instructions to update.
Is something described here not working as you expect it to? It might be a Known Issue. Please check with the Issue Tracker at issuetracker.unity3d.com.