How to claim the 3 Month Xbox PC Game Pass addon included in my Lenovo desktop?

Hey guys, I bought Legion Tower 7i with the add-on of 3 Month Xbox PC Game Pass. But I don't see any ways to redeem it. I looked in my xbox app on this Lenovo PC, Lenovo Vantage, and my lenovo invoice page, and searched my email, couldn't find anything.

How did you get this? Is it possible that this add-on would expire if I didn't claim it too long after purchase?

Thank you so much!