The expiration of prepaid toll credit

 Prepaid amount validity is three years (premid unit has not been used). This three years is a time period since the last toll transaction. If there was no toll transaction, it is the period since the last charging of this unit. (Public note no. 527/2006 Sb., § 16, rubric 4).
 
The electronic device is not usable in the toll system after this time period.

The electronic device must be returned to the Operator of the Electronic tolling system by personal handover on the Distribution or Contact Point. The deposit is refunded when the undamaged premid onboard unit is returned.

It is possible to return the prepaid amount, but only by claim – it is necessary to send a properly filled Claim form (most important is bank account number and contact).  The list of licence plates of vehicles, of whom the prepaid amount will expire during the next six month, you can find here