I am considering changing a paid app to free with an in-app purchase. If this turns out to be unsuccessful, I would like to change the app back from free to paid.
Is it possible to change an app from paid to free, then change it back from free to paid?
Additional question...
If I change a paid app to free with IAP, can I grant use of IAP to users who bought the paid version?
Yes, you want to check out receipt validation.
You can do it all by checking the value of "original_application_version". But remeber that this is the 'build' number of the version 'bought' by the user, not the version number.
What happens if a user installs a "free" app, purchases in-apps and then I convert the app to paid? I guess the user will keep the access to the app + updates because technically it is "bought"?