It's because some region of the world have time card that add direct time (like 90 day). If you enter those cards, you get flagged as subscribed for 90 day and get veteran bonus.
Some region (like NA) have card that add crysta. Then you select what kind of subscription you want (like 90 day).
When the free period ends (around 9th Sept + the free day Yoshi-P talked for the login issue) you are gonna get automatically billed, and your veteran status will kick in that time.
Don't worry, you're gonna get your mount :)
Pryssant Novio - Ultros Server.
<Chocobo> <cooking>? <Yes, please>!