I’m no lawyer, but this section seems to be OK with making things commercially with the app, as long as you’re not going to sell more than 400 copies of it. 🙂
3. ACCESS AND USE
(A) Our Services are provided for your personal and commercial use except when our Service Content is used to create end products for sale where the lifetime sales of the end product for sale exceeds 400 units. An end product for sale can be either a digital design or physical item created using our Services that you and/or your client intends to sell (an “End Product”). You understand and agree that End Products you create using our Service Content must be a unique implementation of the Service Content, significantly different than the original piece of Service Content and require time, effort, and skill to produce. For example, if you incorporate the Service Content it into a calendar, t-shirt or mug that you design and sell to multiple people, that is considered an End Product.