Well...there is certainly no year pass for DEM150. There are discount cards you can buy which is likely what he was trying to explain.
Don't worry so much...you can buy your ticket at the station or on the train...NO big deal @ all...I do it all the time.
BUT, if you are going to travel on train for multiple days and longer (4 hours+) distances...you should look at some type of rail pass as suggested above.
Email me if you have more questions...
Dorian