in order to participate in any mw3 challenges you must have at least one premium member in your clan that membership was given out once a year and cost 50 dollars a year, this year they have done away with it and are making all mw3 challenges free to enter for anyone, but that according to treyarch/activision will not take place until april of this year, until then you have to be in a clan that has that premium member, hope this helps you guys out, cause i see no one else answered your question. oh by the way black ops 2 challenges are completely free to enter from any clan, no premium is needed good luck and hope to see ya on top.
You have to be a premium member to earn XP for your clan. If you don't have a premium member in your clan, you will not get XP for your competitions or enlistments.
Overall, you have to have a premium member in your clan to level up. I know it stinks. I have a clan with no premium members in it either. Hope this helped.