How do you know that you're not under the Law? God says that His law will never pass away until heaven and earth pass away...
How Do you know you're not under the Law?
The old heaven and the old earth passed away for good in 70AD.
Paul knew he was living in the end of the ages.
So did the writer of Hebrews:
(Heb 9:26) Otherwise, He would have needed to suffer often since the foundation of the world; but now once at the consummation of the ages He has been manifested to put away sin by the sacrifice of Himself.
As did Peter:
(2 Peter 3:3) Know this first of all, that in the last days mockers will come with their mocking, following after their own lusts,
As did John:
(1 John 2:18) Children, it is the last hour; and just as you heard that antichrist is coming, even now many antichrists have appeared; from this we know that it is the last hour.