Zend Optimizer
Optimization Pass 1 enabled
Optimization Pass 2 enabled
Optimization Pass 3 enabled
Optimization Pass 4 enabled
Optimization Pass 9 disabled <--- I need enable
Zend Loader enabled
License Path no value

"php.ini"
zend_optimizer.optimization_level=15
zend_extension_manager.optimizer=/usr/local/Zend/lib/Optimizer-3.0.0
zend_extension_manager.optimizer_ts=/usr/local/Zend/lib/Optimizer_TS-3.0.0
zend_optimizer.version=3.0.0
zend_extension=/usr/local/Zend/lib/ZendExtensionManager.so
zend_extension_ts=/usr/local/Zend/lib/ZendExtensionManager_TS.so

Please let me know how to enable it.

Why do you need to do that? You should ask it at Zend's official forum as I am not sure about it.