Your subscription can be used on multiple devices. Go grab the mat, download the Asana Rebel app on your other devices and log in using your account details.
Make sure to tap Login, not Get started, when you log in.
If you don't immediately have access to the subscription, make sure to use the same email address you first logged in with, including any capital letters. Should the problem persist, contact us here and select Access Issue.
Please note that in-app purchases are not available for family sharing.