Adobe has published a short article regarding certification renewal. It says:
Starting on July 1, 2019. Specifically, all Adobe certifications will now expire after two years and require renewal. Renewal consists of passing the latest version of the applicable Adobe certification exam. This adjustment helps ensure all ACEs remain current and can create value for customers using the latest features and functionality of Adobe's solutions, which are constantly evolving to stay ahead of a rapidly changing customer experience market.
You can read the full article here: https://www.certmetrics.com/adobe/candidate/news_item_details.aspx?naid=1