This is a result of the eternal feud between Apple and ComiXology's parent company Amazon.

The iOS version doesn't allow users to directly purchase books in the app itself, instead directing them to the ComiXology website. There is one other app-specific quirk worth noting. The app lacks that feature, which can result in a lot of trial and error if you're simply trying to find a new Batman comic to read. The website at least offers an option to filter search results to include only those books available on Unlimited. There's no option to view a full, organized list of all available Unlimited titles. Life-long comics fan Patton Oswalt took to Twitter to register his complaints.The one downside to Unlimited being integrated with the rest of ComiXology is that it can be difficult to navigate the Unlimited library if you don't know exactly what you're looking for. But as we’ve seen in the past, when a legitimate business makes it harder to give you their money, piracy tends to increase. The volume sold of comics these days is so small that our personal business and purchases matter greatly. I 100% do not advocate the piracy of comic books. The best place to buy new comics, which made it easy to buy new comics every week has gone the way of the Kindle store. I no longer buy physical copies for a lot of reasons (limited physical space being the main one) and digital is my preferred avenue for consumption. Overall, I think this is bad for the comics industry. My underpowered Lenovo Duet Chromebook handled loading, sorting, and grouping my 3800 issue library in under 5 minutes, thumbnails downloaded and read/unread status included. I sometimes questioned if I had a good enough tablet because of just how poorly the ComiXology app performed. The app is miles ahead of where it was before.

Cost of comixology unlimited