Need help with listview, pdf selling app

Hey all koders,
Hope you all are doing great. Kodular is a great platform ever.

I want to make an app in which i am selling pdfs, i use colintreelistview connected with Airtable.

As i upload many pdfs in app, i am selling each pdf at different rates.

What I Want?

  1. When any user buy any pdf then the extrabutton of colintreelistview shows text as “view” instead of “Buy”

  2. When a user buys any pdf then he need not buy that again to open, so for that i dont know where to store value so that when app restart again then it detects which pdf user buyed previously.

What i tried

I made the airtable part where admin can upload data like (pdf title, pdf price, pdf link) but when user buy pdf it should open it again without paying for that pdf. That system i dont know how to make.

My blocks

Please if anyone knows kindly help me out… Please.

I am ready to pay also if u make my app.
For info pls PM

Wht’s with these blocks? what do they do and where are they fit in?

I m sorry the images were uploaded wrong. I edited it pls check above message now.