I love the simplicity, but can't imagine a lot of scenarios where this gets used in the real world, just out of curiosity what are the use cases for this app?
I guess one way to monetize it would be to sell integrations with enterprise products (preferably only the ones which are already not free).
You could well make the integrations open source as well, just with a different license (I'd personally require payments only for businesses with more than x revenue).
Oh yeah I've seen variants of this concept, Safenote, comes to mind which expires based off X views or Y days, but nice to see an open source one like yours!
Look up COSS and Open Core to get an idea of how others have monetized.