I am studying IOS developing using swift but I have a problem, now I am studying in-app purchase in swift but I don't know how to use this feature inside my app because I don't have a paid developer account I only have a free developer account and I can't find where to add this functionality to my app from my free developer account (because I need to do somethings in my account then I need to work on Xcode for this feature), so can I use in-app purchase in my app without paid developer account if there is a way please tell me. thank you.
I regret to inform you that you can't use the In-App Purchase feature with free Apple ID, you should enroll to the Apple Developer Program members.
You can check the capabilities availability for each type of account here: https://developer.apple.com/support/app-capabilities/
Good luck with your journey.