I like the Insydium maintenance approach where there's a 12 month reactivation period at the same price as when maintenance is still active. Then after that there is another 12 months 'last chance' period at a higher fee to renew. If the maintenance is not renewed in either of those periods you then would have to pay full amount. If the customer chooses to renew during one of the reactivation periods, it renews from the end date of when the last maintenance expired.