For logged in customer, its possible to show their registered products in the account area or anywhere that's suitable. This will required some knowledge of shop's theme and able to make changes to the theme's HTML.
Here are the steps for putting product registrations in account area:
Go to Shop Admin > Online Store > Themes
Select the Edit HTML/CSS on the top right corner
Locate the template registration should in (e.g customers/account.liquid - This is the same account page that shows order history)
Place the following code into the right place - Make sure it doesn't break the HTML, always good to place it after close tag