For memberships bought via The Independent website:
Independent Membership allows you to use your subscription on up to four devices at any one time.
If you subscribed through the app via the Apple App Store or Google Play Store, you will need to register your In-App bought membership to access your benefits on multiple devices.
If you are unsure if you have purchased your membership via the app or directly via the website, this will be indicated in your bank statement.
You can find the instructions on how to register your Independent Membership here.