In exchange for the pledge, the member state can pursue civilian nuclear technology for energy purposes.
Iran is a member of the NPT but is pursuing nuclear weapons capability.
The West is attempting to enforce Iran's commitment to their NPT pledge. The fact that the leadership of Iran is insane from our perspective gives that enforcement goal a military aspect should the Iranians refuse to back down from nuclear weapons programs.
And in this standoff, the Iranians announce:
The Iranian parliament threatened Sunday to force the government to withdraw from the Nuclear Nonproliferation Treaty if the United States continues pressuring Tehran to suspend uranium enrichment.
So in what sense is Iranian membership in the NPT even relevant? As I've argued, we should expel them from the NPT (though I referred to the IAEA that oversees member nuclear programs in the post. Sorry) and end the charade.
I simply do not believe that the current Iranian government will negotiate away their nuclear weapons ambitions under any circumstances. Only the absolute belief that the West will destroy their regime if they do not halt their nuclear weapons programs would persuade the mullahs to peacefully renounce nuclear weapons. And the mullahs simply do not believe, based on years of experience, that the West will do anything but occasionally issue toothless threats.
UPDATE: Iran will not withdraw from the NPT. Why would they? It isn't as if membership has impeded Iran's drive for nuclear weapons technology. And given that Iran recognizes that Atomic Express membership does indeed have privileges, why don't we expel Tehran and end the charade?