Hi all,
Unless anything has changed, the Legacy API Key access will stop functioning today.
If your integration has stopped working, then check if your integration is listed in the Integrators page via the link below. This will tell if the vendor has updated their software to either use Service Account Keys or OAuth (Authorized Connections).
https://help.keap.com/help/keap-integrators
If your integration is not listed, then check the Identification Guide via the link below for further assistance. If they are not listed in there, then check with the vendor directly. If they are unable to help, then you will need to find an alternative solution.
If you have a custom developed script, then check with the developer to make the necessary changes. If they are not available, there are other developers in this community that maybe able to help out.
Hope that helps.