Just looked at it and it is promising. One question: the price is free but there seems to be in app purchases but I haven't found what they are despite actively

Just looked at it and it is promising. One question: the price is free but there seems to be in app purchases but I haven't found what they are despite actively looking for them. Anyone knows what they are? It makes a ton of difference if it is a mandatory monthly plan that kicks in after I migrated everything, or skins or optional collaboration features etc.