Yes—you can use one Chaos Corona subscription with both 3ds Max and Cinema 4D. The entitlement depends on your plan and also applies to certain older versions.
Use your subscription in both host applications
If you are on the Corona Solo or Corona Premium plan, you can use Chaos Corona in both 3ds Max and Cinema 4D.
Using older versions
This dual-host entitlement also applies to Corona 8 and earlier versions, provided your subscription remained active after the release of Corona 9.