There are basically three forms of membership available to countries not playing cricket at the Test level - Associate, Affiliate and the newest and most informal, New Teritory status. Just to confuse you, this explanation will start at the bottom and go up. I remain a little confused myself here, but I understand New Territories status is a not a form of membership but an informal acknowledgement by the ICC that cricket exists in a particular country prior to a formal application for membership.
Any correction is welcome.
Countries such as South Korea, Samoa, Cook Islands, Tonga and New Caledonia were recently granted this by ICC East Asia-Pacific Development Officer, Andrew Eade. BTW understands Samoa, Tonga and the Cook Islands have applied for Affiliate Membership. According to the ICC's Roger Hill, it is a recognition of the fact that cricket is played according to the rules of cricket as laid down by the Marlyebone Cricket Club. That, and a united governing body are the key prerequsites. The five ICC regional development officers are assigned the task of following the growth of cricket in countries in their region from the embryonic stage to full maturity.