>"If you like it, you purchase again."
This is not what I would call a one-time payment. If you wish to continue to use the website you pay again. That's just not what "one-time" means to me.
It's not confusing, it's just annoying marketing-speak in the sense that (paraphrasing) 'a simple one-time payment' is what customers like when purchasing something. Whereas the offer is not that, the term has been used in any case.
What is offered is 'a subscription without auto-renewal'.
If you really wish to understand my thinking I can elucidate you at length, but it seems we've spent way too long already discussing understanding of a particular piece of marketese.