Seems like a lot of questions on IH revolve around "how can I start charging a monthly fee for my product?"
And - IMO at least - the answer is pretty simple: If you want to charge a recurring fee, you need to provide recurring value.
But that leaves an important question unanswered...
What do you do if your product doesn't provide recurring value?
After all, there are plenty of great products like that... books, courses, software people only need to use once (or very irregularly)...
In our IH quest for 'the holy grail' of SaaS-style recurring revenue, I think we've forgotten that it's possible to build very successful businesses with no recurring element at all.
You can make up for the lack of a recurring fee by introducing upsells and follow-on products to sell to your existing audience and customer base. And - most importantly - you need to make sure your customers refer new customers.
Are you selling a product with non-recurring pricing? What worked for you?