Ways to check for PageLines Theme as active theme http://www.pagelinestheme.com/php-check-pagelines-theme/

check-for-pagelines-dms.php

<?php

if( function_exists('pl_has_editor') ){
  //PageLines v3 (DMS) is the current theme
}

if( !function_exists('pl_has_editor') ){
  //PageLines v3 (DMS) is NOT the current theme
}

check-for-pagelines-framework.php

<?php

if( function_exists('ploption') && !function_exists('pl_has_editor') ){
  //PageLines v2 (Framework) is the current theme
}

check-for-pagelines-parent-theme-string.php

<?php
// used in Action Map plugin ( https://github.com/pagelines/pagelines-action-map )

$dir = basename( get_template_directory() );
if ( 'pagelines' != $dir && 'dms' != $dir ){
  //neither PageLines v2 (Framework) nor v3 (DMS) is the current theme
}

check-for-pagelines-ploption.php

<?php
if( function_exists('ploption') ){
  //PageLines v2 (Framework) or v3 (DMS) is the current theme
}

if( !function_exists('ploption') ){
  //neither PageLines v2 (Framework) nor v3 (DMS) is the current theme
}