P2Use models are sorely lacking as a license option for software.

I don't want a subscription. I want to pay as I use a piece of software.

For instance, I love Obsidian.md and for the most part it's free to use but if you want to sync across multiple devices you need a subscription. With Lightning it's possible to "Pay per Sync" which I would totally do if it was available.

Readwise is another service I would P2U via lightning.