# Retain vs ZenStudy.ai

The clearest difference is ads: Retain at none against ZenStudy.ai's shown. Retain also leads on update cadence (every 3 weeks vs every 2 months) and iOS requirement (15.1 vs 17.6). On price, in-app purchases and device support there is nothing between them.

Both are free to download. Retain sells 2 in-app purchases, starting at $4.99 per month and ZenStudy.ai sells 1 in-app purchase, starting at $14.99 per month. Whichever you choose, the download price is not the number that matters.

Retain ships an update every 3 weeks, ZenStudy.ai every 2 months. The most recent releases landed on October 24, 2026 and October 25, 2026 respectively.

## The numbers

| Metric | Retain | ZenStudy.ai |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (4 ratings)](https://appshunter.io/ios/app/retain-ai-flashcards/id6469217518/reviews)** | — |
| Number of ratings | **4** | — |
| Positive reviews | 88.9% of reviews | — |
| In-app purchases | Yes | Yes |
| Ads | **No** | Yes |
| Update frequency | **Every 3 weeks** | Every 2 months |
| Monetization | Freemium | — |
| Size | 54 MB | 48 MB |
| Requires iOS | **15.1** | 17.6 |
| Devices | iPhone, iPod | iPhone, iPad |
| Age rating | 4+ | 12+ |
| Developer | [Paul Evans](https://appshunter.io/developer/1711681032) | [ZenStudy Technologies - FZCO](https://appshunter.io/developer/1782979211) |

## What reviewers say

### Retain

[App page](https://appshunter.io/ios/app/retain-ai-flashcards/id6469217518)

This minimalist flashcard app uses AI to help you create and study. Its intelligent spaced repetition algorithm optimizes review intervals for efficient learning and rapid progress. Choose from different card layouts to keep your study sessions engaging.

**Highlights:** AI-generated flashcards, Customizable card layouts, Spaced repetition algorithm, Minimalist design, Progress tracking

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Premium Monthly | $4.99 | per month |
| Premium Yearly | $29.99 | per year |


### ZenStudy.ai

[App page](https://appshunter.io/ios/app/zenstudyai/id6738932178)

**Features:** macOS Compatibility

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Membership | $14.99 | per month |


## Frequently asked questions

### Is Retain free?

Retain is free to download, with in-app purchases available.

### Is ZenStudy.ai free?

ZenStudy.ai is free to download, with in-app purchases available.

### Do Retain or ZenStudy.ai have ads?

ZenStudy.ai shows ads; Retain does not.

### Which is updated more often, Retain or ZenStudy.ai?

Retain ships an update every 3 weeks, and ZenStudy.ai every 2 months. Most recently, Retain was updated on October 24, 2026 and ZenStudy.ai on October 25, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*