How can I save my progress in Farm Merge?

I opened a gold chest and got 270 energy. I started a tree chop for 40E and exited out of the game to play something else while I waited for the timer to count down. I came back to 7 energy, 

I also spent crystals to get a second key to open a chest, but it took my crystals, no key. 

The amount of energy it takes to complete rocks/trees/tool boxes versus how slow the energy regenerates, plus losing energy at random, means it's almost impossible to complete anything. 

Please fix this.