Just had a look at the map updates section and found this as I know there was queries over the free updates.
I read this as you get an update every 6 months so effectively get first 3 years.
Please note the following two information:
1. The current map updates can be downloaded for free here and installed in the vehicle via an SD card. The download and installation can be repeated any number of times. The Map Update Service includes the first five biannual updates that follow the factory-installed map version.
2. Transferring the new map package overwrites the map package currently stored in the MMI.
The currently installed version can be found in the MMI under -> Setup MMI -> Version information -> Navigation database country versions.