Count Logins

login-count.php

<?php
// Create simple meta field to count number of logins
add_action( 'wp_login', 'wd_login_counter' );
function wd_login_counter( $username ){
   $userdata = get_user_by( 'login', $username );
   $login_count = get_user_meta( $userdata->ID, 'wd_login_count', true );
   if ( !is_numeric($login_count) ) $login_count = 0;
   $login_count = intval($login_count) + 1;
   update_user_meta($userdata->ID, 'wd_login_count', $login_count);
}