After reading about them on MN last year I bought a Liber-T toll pass when we went camping in France - was great, saved having to faff about looking for change all the time etc.
The one I bought was the occasional user one. I paid 10 euro for the gadget and paid a monthly usage fee only during the months that it was used (which was just July!) and the charges went onto my credit card.
Is it okay to use the same one in August this year or do they run out?
TIA :)