Yesterday, a friend told me that Facebook allows users to host a shop as an app.
Is this allowed now?
Where can I find information about this?
Facebook owns a payment system available through the API to any developer wishing to earn money.
Facebook Payments is a payment system that offers a safe, easy and fast way to pay for digital and virtual goods in games and apps across Facebook. Source: https://developers.facebook.com/docs/payments/build/
This payment system is only dedicated to games and app for which we get nothing but some virtual goods.
The Payment system doesn't allow you to sell and send anything.
You may not accept Credits as payment for tangible goods, including as payment for anything that may subsequently be used to acquire tangible goods, defined as any good that is physically delivered to a user. Source: https://developers.facebook.com/policy/credits/
Anyway, it would not have been a good idea... see:
Facebook will earn a 30% service fee, plus any applicable sales tax or VAT, in connection with each Facebook Payments transaction on our platform. Source: https://developers.facebook.com/policy/credits/
In that case, you are only displaying the content of your site under an app. An app which could be visible on your own domain (www.yourdomain.com) as well as on your Facebook app (www.facebook.com/yourapp). Your website/app could eventually lead to a payment page which is independent from Facebook. So, a webshop through an app is allowed, as soon as it doesn't use Facebook Payment! The only restriction from the Facebook policy is:
You will not sell or purchase any data obtained from us by anyone. Source: https://developers.facebook.com/policy/