Answer to Stack Overflow Question:
The key for user registered date (actually date and time) is user_registered. It’s saved as a string in Y-m-d H:i:s format. “DD/MM/YYYY” isn’t a PHP/Wordpress date format, but I think you mean d/m/Y.
How you extract the data will depend on how you’re getting the user. So for current user you could try:
$registered_date = date( 'd/m/Y', strtotime( wp_get_current_user()->user_registered ) ) ; echo 'You registered on ' . $registered_date . '.' ;