The PINs will expire if they are not used within an activation time frame. Please see the guide below.
One-Time PINs must be used within 24 hours after creation
Permanent PINs must be used within 24 hours after creation
Duration PINs must be used within 24 hours of start time
Bluetooth keys must be claimed within one hour after creation
PINs should just be in the Inactive tab after they have been used or after their expiration date.