I think the Restore Online Shoppers’ Confidence Act [1] made this impossible in the US. Instapaper would be a third party seller and would be bound by new data pass rules:
(2) the post-transaction third party seller has received the express informed consent for the charge from the consumer whose credit card, debit card, bank account, or other financial account will be charged by--
(A) obtaining from the consumer-- (i) the full account number of the account to be charged; and (ii) the consumer's name and address and a means to contact the consumer;
and
(B) requiring the consumer to perform an additional affirmative action, such as clicking on a confirmation button or checking a box that indicates the consumer's consent to be charged the amount disclosed