You can purchase it from Google Play or Apple App Store compatible devices. If you log in with the same account, you can also use the premium features on this device.
Paid plans are billed via your Google Play account. Your paid plan will be automatically renewed. You can stop the auto-renewal at least 24 hours before the expiration date. Paid plans are renewed between 24 hours prior to expiration and the end of the expiration period. You can change your registration details or stop auto-renewal from the Google Play settings page after purchase.