Apply the License Key 
If you haven't get a license key, please check out how to obtain a license key.
ComPDFKit Conversion SDK currently supports offline authentication to verify license keys.
Learn about:
What is the authentication mechanism of ComPDFKit's license?
Copy the License Key 
Accurately obtaining the license key is crucial for the application of the license.
- In the email you received, locate the XML file containing the license key.
- Open the XML file, and determine the license type based on the <type>field. If<type>offline</type>is present or if the field is absent, it indicates an offline license.
Offline License:
xml
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<license version="1">
    <platform>ios</platform>
    <starttime>xxxxxxxx</starttime>
    <endtime>xxxxxxxx</endtime>
    <key>LICENSE_KEY</key>
</license>Online License:
xml
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<license version="1">
    <platform>ios</platform>
    <id>APP_ID</id>
    <starttime>xxxxxxxx</starttime>
    <endtime>xxxxxxxx</endtime>
    <type>online</type>
    <purchasemodel>subscription</purchasemodel>
    <key>LICENSE_KEY</key>
    <secret>LICENSE_SECRET</secret>
</license>- Copy the value located at the LICENSE_KEY position within the <key>LICENSE_KEY</key>field. This is your license key.
Apply the License Key 
You can perform offline authentication using the following method:
Before using the classes and methods of the ComPDFKit Conversion SDK in your project, you need to initialize the SDK with a valid license key. If you don’t have a license key, feel free to contact the ComPDFKit team to obtain one.
objective-c
#import <Foundation/Foundation.h>
#import "conversion.h"
#import "common.h"
// Verify the license
NSInteger licenseResult = [LibraryManager licenseVerify:@"<your_license_string>"];
if (licenseResult != 0) {
    // Handle license error
}