I pay for the $0.99 tier of extra storage. It is automatically charged to my Apple Card. The past few months Apple has reversed the charge if I have no other charges to the card, effectively giving me free additional storage for the month.
I’ve only used my card twice since getting it - once for my iPhone 11 in December and this month for my wife’s Apple watch.
Thought it was interesting they did this rather than make me pay the $0.99 each month.