With 816 MB of graphics memory, your game will only run on desktop computers. What is the usual RAM size of video cards nowadays? 2 GB? 4 GB? Consider about half of that as your upper limit for a project. If your game is supposed to run on tablets or phones, aim for 100-400 MB max for the whole project (and not for each object).
Animation tools basically move, resize, warp and twist sprites. Construct can do the same, no need to store a large sprite over and over in a series of huge images. The key is to import the "move, resize, warp and twist"-commands from your animation tool into Construct. This can be done with Spriter, not with Moho.
You should consider to either switch to a programming tool that does support Moho exports (like Unity) or to an animation tool that is supported by Construct, like Spriter.
https://www.youtube.com/watch?v=jJm3jNertz0
https://www.slant.co/versus/5514/17370/~spriter_vs_moho-12
it's not 816 Mb of graphics memory. It's more like RAM, because each 17 Mb animation raises RAM usage for 40~ Mb's. So, 48 animations will be like 2-3 Gb's of RAM, not GPU, because those frames data located in RAM when object is on the layer. I decided to make 48 objects, each one have each animation set, so it will eat only 40 Mb's of RAM and if I want to switch animation just delete previous one object and put the other one. This is only solution I found how to import complicated animations with good framerate with minimum quality lost and maximum optimisation.