I don't have this problem. I bought iOS Anki app for myself many years ago. What I found hard is to recommend it to others, who never heard about spaced repetition yet, especially to young students, who arguably is the main target audience for this kind of tools. They just not jumping into buying 25$ app to try it. As soon as you start mentioning switching to laptop, using web/desktop - they're not jumping into it either. I don't know maybe you all have different experience, but that's what I experienced over the years and it always felt sad, because this price is a prohibitively high for many people.