Akatsuki?

[Onidemon]

It's quite Simple, They will probably put up a cap in regards to how many cards a free company can hold, my guess is probably just one. Also, they will probably set a timer on the cards where if it is not used after X amount of time, the primal breaks free from your control and you lose the card.

If they don't add these rules then it will be quite stupid because one day a bunch of trolls will decide to keep their cards for months just to mess with people.

EDIT: Another cool idea would be stealing cards from free companies. They could make it possible through PVP where when a free company that hold a card is defeated by another free company then they lose that card. Which i know won't happen if that company doesn't do any PVP unless they are forced to somehow but they can also come up with different ways of giving you the option of snatching cards from companies that hold them, ways that may not involve PVP that is.