I can tell you 2 simple solution one is you can check in you Db and return the Expiredate and status as true or fales for example if expiry date is > then 30 days + todays date then it should return the false .If todays date add 30 days is < expirey date then return true and display your warning message.
here is sample SQL query for you.
declare @Expireye datetime,
@eDate datetime;
select @Expireye = '12/25/2014 08:00:00'
select @Expireye as expireDate,getdate() as todaysdate,DATEADD(day,30,getdate())as TodatedatePlus30days,
case when DATEADD(day,30,getdate()) < @Expireye Then 'False' Else 'true' END as ExpiryStatus