Please see https://www.spotify.com/premium/ for price after the free offer expires. Cancel anytime. Offer redeemable through September 15, 2023. Only open to users who haven't tried Spotify Premium before. Terms apply.
I haven't tried it, as don't use spotify but saw it on ozBargain so thought about sharing.
Only for new users. Might have to use new credit card which is not registered with spotify, can't confirm.