With the release of 3ds Max 2018 scheduled on April 12, 2017, Autodesk will no longer include NVIDIA’s Mental Ray as part of 3ds Max. Instead the company offers access to the Arnold renderer developed by Solid Angle that was purchased by Autodesk in 2016. Arnold plug-in (MAXtoA) will be included with the 3ds Max 2018 software download, and available on the Solid Angle site.
If you who wish to use Mental Ray with 3ds Max 2018, you can acquire it directly from NVIDIA that also allows free use of Mental Ray for foreground processing while working within 3ds Max.
These changes will affect only users who download and install 3ds Max 2018. Those who are currently using Mental Ray with older versions of 3ds Max are unaffected by these changes as they have perpetual licenses.
3ds Max users will be able to use Arnold out-of-the-box. However, it can only be used for foreground (in-product) processing. Customers will need to purchase additional Arnold licenses if they wish to scale their rendering capability using either background processing, a render farm, or the cloud.
Learn more about these changes on Autodesk website
Learn more about Arnold renderer on Solid Angle