This implies that the author will add an upper limit to the number of these accounts (and that the limit will be low enough to actually matter), being potential

This implies that the author will add an upper limit to the number of these accounts (and that the limit will be low enough to actually matter), being potentially unfair to people who are being denied the option (or at least inequitable when compared with the people who received it). It also places a burden on the author to actively prune free accounts that aren't being used, lest they all end up in the hands of non-users.