Well, one of the complaints of the article was that the app store does not support paid upgrades, so by "a lump sum single payment" grandparent probably meant t

Well, one of the complaints of the article was that the app store does not support paid upgrades, so by "a lump sum single payment" grandparent probably meant that the lump sum would entitle the user to all future upgrades, which is not how the traditional model worked.