I dont like the vaccuum bag approach....
Beans have some gas still trapped in them after the end of degassing and this gas, combined with the oils, water at 9 bars etc.... produce the crema.
When you put them in a container or bag and suck the air out, this reduced the pressure..... increasing the difference between pressure of the gas in the beans and air pressure outside.... sucking out more of the gas from within the bean = less crema. Also coffee oils are volatile (i.e. evaporate) - giving that great coffee aroma.... reducing the pressure will also increase the evaporation rate causing the beans to taste flat.
But having less air there is less chance of the volatile coffee oils going "off" and affecting the taste.
You cant win either way!
But I do what I was told at a professional coffee machine course - store them in bags with one way valves in the back of a cupboard. When you take some beans out of the bag, squeeze as much air out of the bag as you can and reseal it to prevent more air getting in.
And try not to buy more beans than you will use in 3 weeks..... (roasted beans last 3 weeks....) but they could be a week old when you buy them!
Even better - If you use say 300 grams per week.... buy 250gram lots as required..... With your 1 kg, break put them in smaller bags- only opening as required.
There is NO substitute for really fresh beans. And NO way to keep them that way.