I´ve just joined Flying Blue, and am trying to understand the program. My question is, if you reach a new level, how long will you stay at that level?

I figured out that I will reach gold membership by December, but on the KLM pages it says "your Level Miles remain valid until the 31st of December in the year you have earned them". Does this mean that I keep that level just for a few weeks and then be dumped to Ivory in January?