I have a trial account, how can I convert it to purchase?

You can upgrade your account to purchase at any time. Please follow the below steps:

• Launch the Call of Duty game and go to the Audio Settings in the game’s options menu.
• Click on Configure Enhanced Headphone Mode and select the button 'Get Immerse Gamepack'. 
• Please follow the process to finish your purchase. 
• In the settings, toggle Enhanced Headphone Mode off and then on again to ensure your permissions are updated.

Please make sure that you login with the same Activision User ID so that your account is upgraded properly.