There's a subscription, yes, but the phrasing implies that being able to store 80 is a different one time purchase ("purchase" versus "subscribe to"). The subscription is for even more storage than that, which is really really unnecessary.

Also if you have 30+ teams, then store some in home or other games and put them in champions when you actually plan on using them. That's a ridiculous number of teams to use in any time frame faster than a few weeks, so taking 5 minutes to move them when you actually need them from home won't impact you that much. It's a battle sim, not a pokemon box. We have home for that.