Hello nicktoo,
This is the so-called "oldtimer score" or "dice".  It is a way for players to identify the commitment and the conduct of a player.   

The oldtimer score is calculated mainly based on the time spent playing.
It can be negatively impacted by demerits (depending on the duration of the demerit) 
and it will be negatively impacted by temporary bans. Points are deducted.

(This applies to all the games on FlyOrDie, not just checkers.)

Kind regards,
John Stewart