Apollo, the popular Reddit app for iOS, could face millions of dollars in fees as a result of Reddit’s new paid API model. According to an update posted by developer Christian Selig, Reddit could charge Apollo roughly $20 million per year if it continues operating at its current scale.

Reddit announced changes to its API policy in April, which allows the platform to put limits on the number of API requests made by a third-party client like Apollo. But now, we have more details on what exactly this means: Selig says Reddit plans on charging about $12,000 per 50 million requests.

That means Apollo, which made 7 billion API requests last month, would be on the hook to pay $1.7 million per month or $20 million per year to continue operating at the same pace. Selig notes that even if he decided to only keep users who pay to subscribe to Apollo, he still wouldn’t be making enough money to earn a profit. The “average Apollo user uses 344 requests per day, which would cost $2.50 per month,” Selig says, while an Apollo Ultra subscription costs $1.49 per month or $12.99 per year.

“I’m deeply disappointed in this price,” Selig writes. “While Reddit has been communicative and civil throughout this process with half a dozen phone calls back and forth that I thought went really well, I don’t see how this pricing is anything based in reality or remotely reasonable. I hope it goes without saying that I don’t have that kind of money or would even know how to charge it to a credit card.”

It’s still not clear what the future holds for Apollo, though. “My hope at this point is that they listen to the feedback I, other developers, and the community have given them and try to come to an arrangement where both parties can be happy,” Selig tells The Verge. “Outside of that… I’ll have to sit with it for a few more days and think.” Unfortunately, this doesn’t bode well for other third-party Reddit apps, including Rif and Relay, that could be subject to the same kind of fees.

“The costs we shared with Apollo is the pricing per 1,000 API calls, not a monthly bill,” Tim Rathschmidt, Reddit’s director of consumer and product communications, tells The Verge. “Our pricing is based on usage levels that we measure to be as equitable as possible. We’ve been, and will continue, to work with third-party apps to help them improve efficiency, which can significantly impact overall cost.”

Reddit might want to take into account the number of users who might want to leave the platform if their favorite client no longer works. Apollo, for example, enables a bunch of great features for browsing Reddit, like faster loading pages, customizable gestures, a better comments layout, and more. Many users in Selig’s update thread are saying they will leave the platform if Apollo and other third-party apps no longer work, with one user stating, “Without third party apps, I’ll abandon Reddit like I abandoned Twitter.”

Update May 31st, 5:59PM ET: Updated to add a statement from Christian Selig.