CHEMISTRY COMMUNITY

If a compound does not have resonance, does that mean the only lewis structure it has is the most stable?

Yes...

But be careful that when you draw the Lewis structure you draw the most stable one that gives the lowest formal charges on each atom. Or for example if there is a molecule with an overall negative charge where the negative charge can either be drawn on an oxygen or on a carbon, the most stable structure is with the negative charge on the oxygen since oxygen is more electronegative than carbon and is more likely to hold a negative charge.

Yes as long as you create a correct Lewis Structure for the compound that has the lowest possible formal charge

That is correct, and it should also be the only possible way to be drawn/structured?