A club membership for individuals, usually the children of regular members, who have not yet attained the age required for regular membership but are too old to be afforded membership status on the basis of their parents' membership is called a membership.

junior membership                            

Explanation:

A Junior refers to the DAR affiliate aged 18 to 35 (till his or her  36th anniversary). An individual holds associate membership throughout the Federal Community, chapter and state society. That person  can represent as both an officer and president at all concentrations if eligible. For quite a number of reasons, younger members join the DAR, and have various interests.

Thus, from the above we can conclude that the correct answer is junior membership.