I'm hoping somebody can help advise here. We sell products to photographers that enable them to design and manage websites and photo albums on their own server. Essentially, our paid software is installed on their servers. I am about to embark on an iOS app that enables our customers to manage the albums on their self-hosted sites from an iOS device. We would be selling this app, so not a free download. My question is, does this model work within the T&Cs of the App Store? The model being a paid app requiring paid software on their own servers to function. Note that we do not offer a service or have any subscription model. Alternatively, if we were to offer a free browsing-only app with an in-app purchase to provide full functionality would this be allowed? That is a free app that would be partially functional if the customer has our paid software on their server, fully functional if they have both our paid software on their server *and made an in-app purchase*, and effectively not functional at all if they do not have our software on their server, irrespective of whether they have made an in-app purchase or not. Thanks in advance for any advice on this.