How to upgrade from free to paid version and maintain established player prefrence data?

i am getting ready to launch an app that has a free ad supported version and a second version with the ads removed.

My problem is how to transfer the playerprefs data from the free version to the paid version. If a user establishes data in the free version and decides to pay then that data needs to be ready in the paid version. If not the user would be very upset. My question is how to best set this up.

I currently have a paid "pro" version that differs in name and bundle identifier by adding "pro". Consequentially, when you install the paid pro version, your previous player data is not there and you have a fresh start.

• I have two apks (android), one for free and one for paid.

• each apk has its own name and bundle identifier

• I need playerprefs data to transfer from free to paid.

Any solutions to make the data transfer? or restructure upgrade process? or alternative local data storage method that both pro and free access?