In its release, the company explained that Opera Max had turned into a product with a "substantially different value proposition" as compared to their browser products. Because of this, Opera Max gave Opera a different focus. Along with the decision to drop Opera Max, Opera, the company, plans to focus on their browsers and other services they have lined up.
It's easy to see why Opera decided to let go of the Opera Max service. Back when it was first launched in 2014, the service provided users of the Opera browser a system-wide data-saving proxy that funnelled app data in order to compress images and videos. Because of how helpful the service was, it became a hit and has since been installed over 500,000 times. Considering this was the case, the service deviated from the company's main product.
If you search for the app on Google Play Store today, you won't be able to find it anymore. Meanwhile, those who have the app installed on their device may continue using the service. But now that Opera has made this announcement official, it's likely the app won't be available for a long time as its servers could be shut down real soon.