Unity have released a statement about their approach to GDPR:
https://unity3d.com/legal/gdpr
According to this page, from May 25 they will embed consent controls directly inside Unity Ads:
How will Unity allow players to decide if they receive targeted ads?
Unity will provide players with the ability to opt-out of targeted advertising. The first Unity ad that a player sees in each game will provide them with information about the data we collect, a link to our Privacy Policy, and the opt-out option. Players will be able to change their privacy setting any time they see a Unity ad via the Info “” icon.
They go on to say that this functionality will automatically become available if Unity Ads SDK 2.0 or newer is used:
As a publisher, do I need to update my Unity Ads SDK?
If you are using Unity Ads SDK 2.0 or newer, GDPR-related changes will be automatically available to you no later than May 25, 2018. If you are using SDK 1.5 or older, we recommend that you update the SDK; otherwise, Unity can only serve contextual ads for your players.
This Corona forum post suggests that Corona is already using SDK 2.0 or later:
https://forums.coronalabs.com/topic/68416-unity-ads-plugin-update/
So it seems that these changes should apply automatically to Corona apps using the Unity Ads plugin, with no further SDK or plugin update needed. Is this the case?