Access Token

I want to set my access token with in 1 year here is my code whats the wrong in my code because its not working my expires_in was not change .

if(isset($_GET[‘code’])) {
// Setup the HTTP Header Content Type.
$headers = array(‘Content-Type: application/x-www-form-urlencoded’);

// Setup the Fields we are going to post.
$fields = array(
‘client_id’ => $client_id,
‘client_secret’ => $client_secret,
‘code’ => $_GET[‘code’],
‘grant_type’ => ‘authorization_code’,
‘redirect_uri’ => $redirect_uri,
‘expires_in’ => 31536000

// Setup cURL so that we can post the Authorization information.
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, “[url]”);
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
curl_setopt($ch, CURLOPT_POST, count($fields));
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($fields));
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
// Execute cURL and get the result back.
$result = curl_exec($ch);
// Close the cURL connection.
// Get and store the Tokens.
$response = json_decode($result);

Here is my result : stdClass Object ( [scope] => full|cjw616[url] [access_token] => vwiJuGJM6od2vnAzwDXNfZQOjV18 [token_type] => bearer [expires_in] => 86399 [refresh_token] => VpQEaJN0GueYAqRQZfbzOYzhu1ZG8FFO )

See my expires_in is not change

This is reference site : Using OAuth 2.0
Here define expires_in parameter

Please give me solution what i do.