BYOK frees application developers from being inference resellers and enables generous free tiers where you convert users because they love your app and want advanced functionality, not because it has a 7 day free trial then they can't use it anymore.

Also, subscriptions are a garbage business model from the user perspective, it's literally a dark pattern. They make sense for things with recurring costs to provide, but for instance, I should be able to buy a copy of Cursor and plug my key in and use it forever, and only shell out if I want upgrades. It's a subscription service because they're trying to bleed their users dry, and I'm sick of it.