To the OP:
Download it through steam if you want it in your list of games. The 'three machine activation' drm exists for the game whether its through Ubi or Steam, but that's fairly ambiguous - it could mean three machines at any one time, or three new installs on different machines. The only thing I suggest is that you uninstall before making any changes to your system, or if you buy a new system.
Anyway - I've done some research on Anno, because I thought it looked cool, but it hasn't been scoring very well, and a number of friends who have played it have said that the customisation and selection of buildings is very poor and that generally gameplay is short-lived and gets dull quickly.
Civ 5 is still pretty much the same as all the other Civs and Sim City can be fun but its getting real old.
Settlers : Rise of an empire is fun and 1701 AD is far better than Anno for city building, economy and resource management.
If anyone can suggest any better ones I'd be pleased to hear it - there's not many games like this being developed these days.
Just don't suggest stronghold. ;-)