您可以将两个应用程序（在***上搜索以集成这两个应用程序）完全集成，但这不会解决您的问题付费用户的方法。

这是我要做的事情

第1步：实施应用内购买免费的应用程序（测试它 - 让它活着）

第2步：更新prod应用程序（向用户显示消息以迁移到免费应用程序）。由于您只有付费用户 - 为每个用户提供促销代码是安全的，因此您需要在付费应用中使用某些逻辑来为每个用户创建唯一代码 - 请参阅此链接以创建促销代码，该代码可以在 https://developer.android.com/google/play/billing/billing_promotions。 HTML＃工作流程

第3步：所有付费用户都可以在免费应用中兑换促销代码。

第4步：从Google Play商店中移除付费应用程序

PS：如果您有付费用户的本地文件，数据等，您仍然需要将它们迁移到免费应用程序，您可以使用共享资源，服务器端编码或仅使用ContentProvider

我认为没有其他简单的方法可以做到这一点。

I did big mistake with monetisation my app in Google Play. I separated my app to 2 versions (with different applicationId), but now I would like to have one app with in-app purchases to Pro version or something like unlocker. I have a lot of downloads my pro version app so I can't just remove it from Google Play. Does anyone faced with this problem ? Any workarounds ?

You can definitely integrate both apps ( Search on *** for integrating both apps ), but that will not solve your paid users approach.

Here is what I would do

STEP 1 : Implement in-app purchase in FREE app ( Test it - make it live )

STEP 2 : Update prod app ( Show message to users to migrate to FREE app ). Since you have only paid users- it's safe to give each user a promo-code, you need to work on some logic in paid app for creating such unique codes per user - see this link for creating promo codes which can be redeemed once https://developer.android.com/google/play/billing/billing_promotions.html#workflow

STEP 3: All Paid users redeems promo codes in free app.

STEP 4 : Remove paid app from google play store

PS : If you have local files , data etc with paid users, you still need to migrate them to free app, you can use shared resource, server side coding or simply using ContentProviders

I don't think there is any other easy way to do this.