Pfthb

I am experimenting with openssl in PHP, and found openssl_pkey_get_private to load a key from file with a passphrase.
Do I need to use openssl_pkey_free to unload it before the request ends or will it be freed automatically by openssl when php is shutdown?

Normal variables will be freed automatically, but I am unsure about external resources like this.
I have built a helper function to load the key and cache the instance for multiple use for the current request, and since multiple components in my application will use the key during the request, I want to use the same instance.

Can I use register_shutdown_function to free the key if it's not freed automatically?

Thanks for your help.