WooCommerce hook to generate a Keygen license key after a payment is completed

functions.php

<?php

// Add these variables before running this code
$KEYGEN_PRODUCT_TOKEN = '...'
$KEYGEN_ACCOUNT_ID = '...'
$KEYGEN_POLICY_ID = '...'

// Add a hook after payment is completed
add_action('woocommerce_payment_complete', 'generate_license_key_after_payment_complete');

function generate_license_key_after_payment_complete($order_id){
  $order = wc_get_order($order_id);
  
  // Get the ID of the order
  $order_id = $order->get_id();

  // Get the ID of the customer
  $user_id = $order->get_user_id();

  // Generate a Keygen license for the user
  $response = wp_remote_post("https://api.keygen.sh/v1/accounts/${KEYGEN_ACCOUNT_ID}/licenses", [
    'method' => 'POST',
    'data_format' => 'body',
    'blocking' => true,
    'headers' => [
      'Authorization' => "Bearer ${KEYGEN_PRODUCT_TOKEN}",
      'Content-Type' => 'application/json',
      'Accept' => 'application/json'
    ],
    'body' => wp_json_encode([
      'data' => [
        'type' => 'license',
        'attributes' => [
          'metadata' => [
            'woocommerceOrderId' => $order_id,
            'woocommerceUserId' => $user_id
          ]
        ],
        'relationships' => [
          'policy' => [
            'data' = ['type' => 'policy', 'id' => $KEYGEN_POLICY_ID]
          ]
        ]
      ]
    ])
  ]);

  // TODO: Email license key to user, etc.
}