Explaining that she’s seeking a “change of life” that includes more time with her children, Pam Keehn said last week she will retire from Siltanen/Keehn by the end of the year. Keehn, 44, launched the El Segundo, Calif., independent as president with chief creative officer Rob Siltanen in January 2000. While the shop once boasted the $180 million Gateway account, it is down to three clients and an estimated $12-14 million in billings. Siltanen said he has no plans to close the agency and will assume Keehn’s duties until he recruits a new partner.