When do rewards expire if we've 'claimed' them?

Hello,
I have a free unlimited mobile line for a year from xfinity, included with my wifi purchase. I've 'claimed' the offer, and it is showing that the offer ends 9/30/25. Does this mean I have until 9/30/25 to use the offer, or is that just how long the promotion will be offered and since I've claimed the offer I will be able to use it after the expiration date? I would need to use the line by 10/17/25 so I'm trying to decide when to set up my free mobile line. Thanks!