One of the major, but often overlooked, systems in Ashes of Creation is the mount system. While we do not have all the information about the system, we do have enough details to lay out the baseline information about mounts.
There are going to be three tiers of mounts in Ashes of Creation.
Tier 1 mounts are ground mounts such as Horses. Your first initial mount will be acquired early in the game and will be a Tier 1 mount.
Tier 2 are going to be gliding and jumping mounts such as the Hippogrphys and Gryphons, and the other more elaborate mounts like the Thundering Bolt Beast and the Glimmering Geode.
Tier 3 mounts also known as Royal Mounts, are the only mounts capable of True Flight, these are Dragons as well as the upgraded version of the Gryphons and Emberstorm Dragon that was earned in Apocalypse.
There are also underwater mounts, however, I have been unable to get a direct answer if these fit in a tier, or if they are a tier all of their own.
Royal mounts are specifically designed to be rare, in fact the only guaranteed way to have a flying mount is to be one of the 5 Monarchs (Guild Leader that controls a castle) or one of the 5 Metropolis Mayors.
Additionally there will be the occasional legendary drop which drops a Royal Mount egg, which will provide a temporary Royal Mount (14 days to one month lifespan).
Undermounts are a flying mount that are part of the Castle Siege system. The owner of a castle will be able to grant up to 5 undermounts to guild officers during a castle siege. These mounts are flying mounts and they only function during the castle siege day. More on this topic as it becomes available.
Mounts in Game will be acquired through the Gathering skill of Taming or through the Processing skill of Animal Husbandry or by purchasing them from other players. More information will be presented in the specific sections for these professions when we have that information available.
The majority of mounts will not have a lifespan and will live forever.
Royal Mounts (aka flying mounts) do have a fixed lifespan. Your Royal Mounts from your position as Mayor of a Metropolis or King/Queen of a castle lasts until your term is up (you get voted out or you lose your castle). For Legendary Eggs you find in the wild or through the course of the story, it will have a lifespan of 14-30 days and then it will perish.
The first and most important thing I can say about the Cash Shop and mounts is that the Cash Shop is not selling Mounts, they are selling Mount Skins.
You will not get access to a mount because you purchase it in the cash shop, instead you will still have to acquire a mount in game either through Taming, Animal Husbandry, or by purchasing the mount you want from another player.
After you have acquired the mount you want through in game means, then you can put a cash shop skin on it.