using wp strings in page i.e. $user_identity

Firs off, the site is hosted on Hostgator and I am using the Exec-PHP plugin to allow me to add <?php ?> within posts/pages which works like a charm.

I have been trying to add a string variable used in the header to my page. The following is a very simplified version.

<?php
if( $user_identity ) echo 'Welcome back';
else echo 'Welcome guest, please enjoy your stay';
?>

I am only receiving the else function because wp is stripping out the string variables. Which I found out by doing this…

<?php echo $user_identity;?>

there is no result but the same string can be found right next to ‘howdy’.

My question, how can I extend the use for the wp string variables beyond the header?