This is straight from the Horses Mouth .
Will my credits expire? How to calculate the valid date?
According to the Terms of Service, Qpid Credit can be used for 180 days from the date of purchase. Credit older than 180 days old in the Account will become expired.
To help members make better use of credits, Qpid Network only adoptes the date of your last purchase as the base to calculate valid date. That is to say, all of your rest credits will be valid for unified 180 days once you make new order successfully. For example: You have 3 credits and it will be expired 20 days later, now you purchase another 10 credits, then the expiry dates of your previous 3 credits will be 180 days later but not 20 days later. You need to use up your 13 credit in the next 180 days. .