Add upgrade class for data migration

admin/core/packages/1.3.39.php

@@ -0,0 +1,27 @@
+<?php 
+	
+	// If this file is called directly, abort.
+	if ( ! defined( 'WPINC' ) ) {
+		die;
+	}
+
+	/**
+  	 * This populates all existing UM users with meta_key `last_login` as `user_registered` if the meta key doesn't exist.
+  	 * Target Version: 1.3.39
+  	 */
+  	
+	global $wpdb, $ultimatemember;
+  	$wpdb->query('INSERT INTO '.$wpdb->usermeta.'(user_id, meta_key, meta_value) 
+	   			SELECT uu.ID, "_um_last_login", uu.user_registered
+	   				FROM '.$wpdb->users.' AS uu
+	   			WHERE 
+	   				uu.ID NOT IN(
+	   						SELECT user_id FROM '.$wpdb->usermeta.' 
+	      					WHERE meta_key = "_um_last_login" 
+	      					GROUP BY user_id
+	      			)'
+  	);
+
+
+
+ ?>

admin/core/um-admin-upgrade.php

@@ -0,0 +1,31 @@
+<?php
+/**
+ * This class handles all functions that changes data structures and moving files 
+ */
+class UM_Upgrade {
+
+	function __construct() {
+		$um_last_version_upgrade = get_option('um_last_version_upgrade');
+
+		if( ! $um_last_version_upgrade || $um_last_version_upgrade != ultimatemember_version ){
+			add_action( 'admin_init', array($this,'packages'),10);
+		}
+		
+	}
+
+	/**
+	 * Load packages
+	 */
+	public function packages(  ){
+		
+		 $file_path = plugin_dir_path ( __FILE__ ).'packages/'.ultimatemember_version.'.php';
+		 
+		 if( file_exists( $file_path ) ){
+		 	include_once( $file_path );
+		 	update_option( 'um_last_version_upgrade', ultimatemember_version );
+		 }
+	}
+
+}
+
+new UM_Upgrade();

um-init.php

@@ -13,6 +13,7 @@ class UM_API {
 		require_once um_path . 'core/um-short-functions.php';
 
 		if (is_admin()) {
+			require_once um_path . 'admin/core/um-admin-upgrade.php';
 			require_once um_path . 'admin/um-admin-init.php';
 		}