With the latest update Voice Dream Reader for IOS can be downloaded for free from the App Store.
Also on the App Store there is a subscription listed that costs 59.99$/year.
It seems that this roll out is buggy so it is not clear how it will work regarding the subscription.
Technically the new free app cannot check if someone bought it when it was paid. However it is possible that the developer did update the app in some previous version to register that the user was the user of the paid app, which seems to be the case as it hasn't asked anything when I just started the app. However that isn't bullet proof as if someone hasn't updated the app recently he may lose the record that he was a buyer. Also if someone doesn't have iCloud turned on this record may not transfer to his next device (and it seems that just reinstalling the app will break this record, read more below).
For the purpose of testing, I did uninstall the app. It seems that the app forgot that I was the paid user and I've got the screens asking me to create account and also one mentioning subscription. I have just skipped those screens and the app still works, but I guess that it might be the bug or that I am just temporarily allowed to use the app without subscription.
Just to note that I am a developer of another app (Speech Central) which is completely free when used with VoiceOver. As such I could risk my license for the purpose of experiment. I don't suggest anyone else to do so.