Apple has provided me informed of the player have previously installed my app interface it?

Done before an app, limited free 10 days or so has been downloaded more than 20 w, then transferred to the charge state.
But at that time only 40 points, recently decided to do an upgrade to this app, including image enhancement, bug fix, increase the number of checkpoints.
Here I am facing a problem, upgrade to take care of the old and new users.
We adopt such a strategy, the new user, then only 20 points to play for free, the other levels within the purchase manner.
If you upgrade to the new and old customers alike, then the previously downloaded this app old users, the upgrade to the new version of app after,
The number of checkpoints can play from 40 becomes 20, and so no doubt we must endure the old user curse.

In view of this, we decided to make a judgment, if it is previously downloaded the app user, then we gave him free to open 50 points,
In the previous 40 basis points more than provide 10 to play with him.
If you are a new user, then it is only 20 points to play with, so to solve the old problem of users getting mad.

Question is:
We learned that how a user previously downloaded this app do?
Apple officials have to provide the appropriate api what?
Alternatively, because the user had previously downloaded, then re-download our app even update, there is no way to determine whether the user is a new installation or update the old version?
Jiji Ji, expert help ~
Reply:
Will be purchased record has been purchased, and then tell you the results.
Multi-read, look, IAP relevant information.
Program itself is not remember.
Reply:
Unless you own the background tracking, recording equipment already installed, otherwise no way

Apple is not related to the api
Reply:

2F reply quote:

Unless you own the background tracking, recording equipment already installed, otherwise no way

Apple is not related api

Recording device UUID, can not it?
Seemingly heard previously allowed access to user device UUID, otherwise not allowed on-line ~
But I'm not sure, but there is to say
Reply:

quote 1 floor reply:

will be purchased record has been purchased, and then tell you the results.
Multi-read, look, IAP relevant information.
Program itself is not remember.

Apple users will buy time such data to see if there might be found in time of purchase of the API.
Reply:
With NSUserDefaults save the user setup information, as long as the user does not delete the app, there will be upgraded NSUserDefaults saved, so you can know that the user has not installed the