BYU's website says specifically:

A “representative of BYU’s athletics interests” (booster) is someone who has ever:

Been a member of an organization promoting BYU Athletics (e.g., Cougar Club).
Contributed to the Athletic Department or its booster organizations.
Made any financial contributions to any area of BYU.
Assisted in the recruitment of prospects for BYU.
Provided benefits (e.g., summer jobs or occasional meals) to prospects, enrolled student-athletes or their family.
Been a season ticket holder in any sport at BYU at any time.
Promoted the athletics program at BYU in any other way.

Remember, once you become a booster, you retain that identity indefinitely.