How to get my number of available rides back?

You have a total of 6 rides available in W3:Ride.
When you validate a ride, you have to wait a period of 7 days to have it available again.
In the example below, you can see that the oldest of the 6 latest validated rides was done on the 13th. If you count 7 days, then you know that it will be available to use again on the 20th (the +7days rule).