You've completed your 5 times check-in within the 15-day event period and receive a lucky draw ticket. The accumulated check-ins count will be reset. Once you possess a ticket, the lucky draw button will appear. You can do this more than once, as long as it's within the 15-days period. Let's say you've completed the mission 2 times, then you will receive a total of 2 tickets (The login does not have to be consecutive). If you are lucky and win both draws, then you can keep both horses. However, should the prize pool already be exhausted by the time you use the ticket, then you will receive nothing (It could also happen that you are a very diligent player and you log in for all 15 days.