also can you advice in the first part of my question ? how can I make lite app and allow users to buy the full version.
I’m not sure what exactly you’re asking about. What Rob is suggesting is that you NOT make two separate versions, but have one version that starts off with just the “Lite” version of the code enabled, but with IAP to “unlock” the full version (following the guidance in the link he posted).
If you really want to produce two separate versions, I would think you’ll just have to build the code twice – once for Lite, then make the necessary code changes, then build it again for Full.
But maybe someone else can chime in if Apple or Google prefer/require that you use IAP instead of two separate apps.