openssl_free_key and openssl_pkey_free are probably aliases.
And the preferred one is probably openssl_pkey_free.
(PHP 4 >= 4.0.4, PHP 5, PHP 7)
openssl_free_key — Free key resource
$key_identifier
)
openssl_free_key() frees the key associated with
the specified key_identifier from memory.
key_identifier
No value is returned.
openssl_free_key and openssl_pkey_free are probably aliases.
And the preferred one is probably openssl_pkey_free.