Cost....points. Ken feels bad about diverting the conversation, but Amada-kun does seem to be doing a little better, and that is the most important thing.

Besides, this is relevant.

"So if we gather 'points'," Ken concludes, to be sure he has this right, "we can purchase objects."

"Ken-chan, then!"

"Ah." Wormmon and Ken nod in unison, and Ken finishes Wormmon's statement: "You'll be able to evolve!"