Follow the 5.2 integration instructions in Integration Pages 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 that it is version u5.2 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 syntax. Follow 5.2 Advanced Integration instructions to update.