It’s a mess.
AFAIK it depends on how you’ve purchased the livepass. If done though an app, it’s locked to that app (or at least to apps on that os using that account.) Eg if you download the afl app on your iPhone and purchase the livepass through the app, it’ll be locked to that app (or at least to devices signed into the account used to download the app, eg an iPad and an iPhone using the same appleid.)
However if you bought the livepass off the afl website or get it as part of a Telstra thing, then you can use those credentials (eg your Telstra id) to sign in all over the place.
This is as much as I remember it, it’s been a couple of years since I checked.