It's all fun and games until you hit version n+1 or n+2, and often realize how slow many customers are to upgrade the library. Then there are the potential conflicts in your own dependencies. And let's not forget the occasional breaking change you introduced.
You are now sacrificing the money saved by not hosting to maintain what will likely be a growing matrix of possible versions, underlying assumptions, and my personal favorite: weird customer deployment scenarios that break your library functionality. Bonus points if you are developing in a language without strong typing, or need to integrate with a dependency manager.
Plus, if there was anything about your service that leveraged unique algorithmic improvements or some other proprietary tech, it is now at the mercy of anyone with a decompiler and sufficient time.
I suspect the author may change their mind if exposed to scaled up solutions and technologies.