You know the old joke about being involved vs being committed, the punch line is that in a bacon and eggs breakfast the chicken is "involved" and the pig is "comitted." So it is with web service APIs.
If you have 'free' API access then you are providing some benefit to the web service (whether you know what the benefit is or not), when you have a 'paid' API access you are a customer of that web service.
If you're paying for a service as part of your product, you need to understand how your costs may change over time, and generally you put into the contract language under what conditions and time frames the price can change.
This is one of the essential differences between building products and building demos. Just like an engineer might build a circuit that works to prototype something, they will go back and do all the edge case and tolerance analysis prior to putting it 'into production.' If you've never shipped a product before it can sometimes be a painful learning experience to get these sorts of lessons the hard way.
Thank you for this. It's not anecdotal to simply say "don't rely on platforms". Be weary of platforms that are free. They do have risks. It's important to understand those risks before thinking you've just hit a gold mine.
Personally, I wonder if this sort of pushback will drive us towards a more standards-ish way of approaching platforms where it won't be enough to simply provide an API – to get use, you'll need to make it a more standardized API that provides a more standardized sort of data – because only when we have those sorts of standards can we hope of it being safe to develop based on someone else's free API – because I know if I need to, I can substitute in (or combine) some other data source.
Relatedly, Right now, what I think we're seeing is a lack of real competition of direct substitutes. There is nothing exactly substitutable for Twitter quite in the way that products ranging from Heinz Ketchup to the Chevy Malibu face real, direct substitutes, rather than a more abstracted category substitute (i.e. Facebook is similar to Twitter, but it's not a perfect substitute). As such, switching costs are higher and it makes development for a specific platform more risky.
I'd say avoid platforms that lock you in to that vendor, free or not. I've read of paid accounts being shut down just as unceremoniously. Or prices were increased 10X. Even when not locked in, one should be ready enough to move to another vendor without too much problem.