Do I need a sponsor?

I’ve been sober for over a decade without AA, but I go to therapy every week and have done an IOP program. I decided to join AA to join up with people who have the same disease as me and to keep me in check. I wasn’t intending on getting a sponsor but I was told I can’t successfully be in the program and stay sober if I don’t have one and don’t work the steps with a sponsor. Is this true? Do I HAVE to have sponsor in order to remain sober for life?