I'm using studio one 6.6 and when i open melodyne it says not supported , it was working fine in 6.5

 

You could use Revo Uninstaller to cleanly remove Melodyne, then reinstall it. That is, if you did the same thing for the 6.6 update of Studio One. If not, you might want to try that also. I would check to make sure you still have the apps/plugins firewalled correctly. Add host file entries if you have to.

Here's an interesting note from the Celemony website:
https://www.celemony.com/en/melodyne/editions-and-technical-matters
Presonus Studio One

Studio One, thanks to its support for our ARA Audio Random Access technology, integrates Melodyne in a way that is particularly user friendly. We have tested the latest versions of Melodyne 5 with the following configurations:

Studio One 6.6 (ARA) under:

• Windows 11
• macOS 14.4 (Intel)
• macOS 14.4 (Apple Silicon native)

Please also take note of the information and tips on the operation of Melodyne in Studio One in the Help Center and in the FAQ.