Add paid feature to existing React Native App

I have an E shop that's already built, and in working conditions, I need some some to add a paid feature that allows users to post items for sale once they pay the subscription. The subscription fee should be in 3 tiers and allows users to post more items according to the tiers. Please write =>" I actually read the post" to start your proposal so I know you read the description. The subscription has to work on the Playstore and Applestore, if you don't have developer accounts but have done this before you can still apply.