I'm a 100K member but haven't flown F9 yet,

I haven't enrolled in the Discount Den perk as I was planning to make it the moment i'm buying a ticket, but just intuitively (looking to maximize the enrollment period?) as I still have not made the research on how it really works.

I received a welcome email today, telling my that I just enrolled on DD, and showing the enrollment date and expiration a year later.

I didn't make it and haven't accessed my account since a long time, maybe it is an automated process and the latest day one can enroll based on the max duration for next year?.

Any input is appreciated as i'm fairly new with F9.