You will get the following error message when trying to create a new database if your 30 day evaluation license has timed out:
That is to be expected, but there can be problems once you have installed a new (valid) 4D license. Sometimes this licensing dialog will come up after installing your new license. There are a couple of things you can do to resolve this issue. Go to the Help menu and select "Update License". From there you can click the "Licenses Folder" button to view your licenses. Your evaluation license should still be in that folder. Try deleting that license. Additionally, make sure you restart 4D after installing your new valid license.