Buy the game.

I guess after unlocking, they will start releasing patches for version 2.*? Because I currently have version 1.8, but it seems to be for the regular game.

No, you can update the game to 2.1.1 even without activating the expansion. But you'll have to do it manually, meaning you'll have to download the patch for your current version yourself (which is important: for example, you can't update a boxed version with a file for the digital version). And one more thing: get the expansion from the same place where you got the original game. Otherwise, it won't work.

Links to Russian patches: 2.1.0, 2.1.1 (boxed), 2.1.1 (digital).