They need to maintain their legal fiction that they own the chips.

You, however, are expected to purchase chips and not return them, even when asked.

They, then, have evidence they can take to court that they have attempted to enforce the license of the chips, and you get to keep the chips. They really only need the history of an attempt to enforce their ownership rights in extreme cases.

You'll recall Kleenex didn't try to enforce it's copyright and now everyone calls all tissues Kleenex, and the courts have said it's now in the public domain solely because Kleenex didn't make an attempt to enforce its rights.

But, remember, the last thing they really want is all their high denomination chips redeemed.