It is very unlikely Iran will live up to this agreement

Why is this?

Because the whole Sunni Muslim World is up in arms against them. Sunnis have finally had enough of all Shiites and this likely will continue to be this way for some time.

Why did this happen?

Because Russia and Iran aided Assad in depriving Sunnis in Syria of all human rights the last 4 or 5 years. This is one of the main reasons ISIS exists today. ISIS was created to destroy all Shiites but also decided to kill all non-Sunnis as well.

Since there are only 165 million Shiites (or Shia Muslims) in the world at present and there are 1.1 Billion Sunni Muslims it is likely without nuclear weapons to threaten the Sunni Nations with that Iran's Shiite Majority could be eventually wiped out by Groups and movements like ISIS.

So, it is in Iran's best interests to develop nuclear weapons secretly. In fact, their very survival as a nation right now might depend upon it long term and short term.

If you see Iran presently as a Hitler in regard to the middle east this would be the most effective way of seeing this.

Unless Iran has Nuclear weapons to threaten Sunni Nations with likely it will end as a viable Shiite Nation this century. So, I fully expect an Iranian Blitzkrieg across the Middle East at some point like they are fighting in Iraq, Syria and by arming the Houthis in Yemen right now to try to destabilize Saudi Arabia and to eventually end or take over the Saudi Arabian Government and Israel.

I don't think you can expect Iran to be honest about these things because their survival as a nation is involved.

It is in their enlightened self interest and survival as a nation to lie to the U.S. and Europe and Russia and create nuclear weapons just like North Korea anyway. They won't survive otherwise.

For IRan, they are using ISIS as a smokescreen along with Russia to do what they want to anyway, despite what the rest of the world thinks.