DL hasn't been actually updated in ages. Current version is 1.50.135. I believe there was a mini-update (simply to test the new patch system or something to that effect) not too long ago, but as far as I know, it hasn't gotten a gameplay update in many many months (probably more than a year), and most likely will not until 2.0.

Bottom line: If you bought DL from a store (recently), got it with the Gold Edition, or downloaded it from Stardock, you've probably got it up to date.

But just in case, would you mind telling us your version number?

I would highly recommend buying the addons, they really improve the game.
You should get the patches using stardock central or impulse (get this).

Check the My Games tab, rather than the Store tab. GC2 should be there, and if you've got it registered already, simply click on it then click the update button.

I recently got Impulse my self. You need to update your registration with Impulse. Start it, look in the upper right corner and there are some small icons, the little white page looking one is update reg. Look up your Serial #, enter it, and you'll be able to get updates through impulse.

Ripper