In order to redeem a Premium gift voucher, please go to your account (via the menu in the top right hand corner). Here you will see your account overview, where you have an option to redeem your voucher (click on the picture to zoom it):
Gift vouchers can only be redeemed on a PC/Mac or in a mobile browser. The functionality to redeem a voucher is not available in our apps yet. The HiQ access itself is however valid for all devices after you have redeemed the voucher on a PC/Mac or in a mobile browser.