Zend Guard Loader is a free runtime application that enables PHP to run the scripts encoded by Zend Guard.
1. Download a copy of Zend Guard Loader from the location below and upload to your server. By default PHP 5.4 is installed on wheezy so select the package Zend Guard Loader (Runtime for PHP 5.4).
2. Enter the directory where Zend Guard Loader is located and extract
tar zxvf ZendGuardLoader-70429-PHP-5.4-linux-glibc23-x86_64.tar.gz
Replace with the name of the file downloaded from zend.com
3. Create a directory where Zend Guard loader will be located
3. Move the Zend optimizer lib to a permanent location
mv ZendGuardLoader-70429-PHP-5.4-linux-glibc23-x86_64/php-5.4.x/ZendGuardLoader.so /usr/local/lib/Zend/
The ZendGuardLoader.so may be located in a different location based on the package downloaded from zend.com.
4. Add these two lines to the bottom of your php.ini to enable Zend Guard Loader (pico /etc/php5/apache2/php.ini)
zend_extension = /usr/local/lib/Zend/ZendGuardLoader.so
5. Restart apache