I have an my app on appstore and currently it's free. I want to make future releases not free but remain this app free for those users who downloaded it before, is there way to make this? Can I check when user downloaded specific app at first and if date is before certain date it remains free otherwise user requested to pay for using this app.
If a user downloads an app and it's free, it will remain free for them in subsequent future updates. Going free-to-paid is fine, for this reason. Generally, going paid-to-free tends to upset the people that paid for your app.
To change the price of your app, you can manage this in iTunes Connect.
If it was free users that already downloaded it own it at all effect.
Setting a price won't affect previous downloads, they'll be able to download future versions as updates without having to pay anything.
Once a user has purchased an app, all updates for that app are free. You can change the price to whatever you'd like, and all existing users will continue to have updates available to them.
It appears that no work is required for you to get the effect you want.
