Uplay's current system on PC is getting pretty close to always-online.
Both you and their servers need to be online in order to launch the game you paid for.
People complain all the time in here that UniSoft's servers are down and they cannot launch their game.
I'm just glad I'm not a fan of Ubisofts output, they really fuck consumers over.
Uplay has an offline mode. You do need to be online the first time you boot up a Uplay game from within Steam, though, so the automated product activation process can complete.
Edit: At least I think the process is automated. The last Uplay game I activated was AssCreed 3 and I don't recall having to enter my key manually.