This is a common question amongst our clients and although we make it clear upon them becoming a member, this questions is likely to be asked to you at least once.
The answer
If your client is on a 10 hour per month plan (or bigger) then YES, their unused hours will roll over into the next month giving them 65 days to use their purchased time each month.
The automatic rollover will only take place if your client retains their plan. If they decide to cancel their account, accrued credit will be lost when their account is closed.
If your client is on a plan smaller than 10 hours per month then unfortunately their unused time will not roll over.