American Express Membership Rewards - Biz Cent. transfer question

I have a Business Centurion and I am resigning from the current company. I am told I cannot convert it to personal Centurion but if I am not going to work for a while (i.e. have no business affiliation) is there a way to maintain Business Centurion account? I guess my question is whether there has to be a business associated with the card to be active.

Thanks in advance.

hchon