How do I purchase a subscription in-app on Apple?

Proceed to the Sportsnet app on your iOS phone, tablet or 4th generation Apple TV. If on your Apple TV, select the Sportsnet+ tab, if you are on your phone or tablet, tap the Watch tab. You will be given the option to sign in or purchase. Select purchase.

You will then be prompted to sign in with your iTunes account. Upon doing so, you will successfully sign up for Sportsnet+.