On the PokerGO website, navigate to the top-right corner of the page and select the Subscribe button. You will be directed to the registration page. Once you input your information and submit it, you will be asked to select a subscription plan. Select your preferred plan and then complete your billing information.
You can get started here:
https://www.pokergo.com/register
To use a promo code, go through your computer or mobile device browser. The respective app stores do not allow the use of discounts. Click the toggle button for your promo code, enter the code, and click Validate.