I am developing an augmented reality virtual dressing room application in unreal where users can create photos, short videos of themselves wearing virtual costumes. The library of costumes are created from 3D characters purchased on the marketplace. Every costume is distributed in a separate .pak file in cooked form that can be downloaded and used only inside the application. Business model will be subscription based, where clients are paying a monthly or annual fee to use the software and the asset library, on trade shows, private events, museums, theme parks, etc.
I would like to know if assets purchased from the marketplace can be used in my application, and distributed such way.
I would like to also know if assets created by epic games such as the paragon characters can be used the same way, and if there are any additional requirements regarding them.