Veteran Medals where given for a player who has reached level 50. There are 4 types of veteran medals wich are: Bronze, Silver, Gold, and Platinum Veteran Medals.
Once you get a medal, you will restart from level 1 and will continue until you reach the last Veteran Medal (a total 200 levels to get Platinum //the maximum amount of levels you can go through is 250).
Your level will reset on new years' and you wont be able to get the Veteran Medals from last year anymore unless you already have them (there will be different medals for each year starting in 2018). Go to Level System for more information on how to earn exp.