Is energy always conserved?

A question I have is that if the ligh appears to be stretched out, wouldn't that imply you see it for longer? Let's say a light beam of wavelength 1 is shot from a galaxy zooming away such that at the observer galaxy it appears to have wavelength 2. The observer would view the wave as having 1/2 energy over 2x the period thus yielding the same total energy. 
Also, I believe that the individual photon does not lose energy as he individual photons frequency is conserved. Redshift applies to the wave not the photon. there are larger gaps between photons making it look redshifted but as said before, the total photon energy remains fixed. Please respond, someone who knows a lot about physics (if physics girl responded that'd be sweet)!