The system will alert you if a regular monthly payment has not been made and if not, your access will be cancelled.
If you haven't actioned any email replies, then you can just resubscribe to the IGNITE Pro membership if your status is showing expired in the account dashboard.
NB: Please note that if you missed a payment and allow your subscription to expire and it was at a lower price when you initially subscribed, you'll be charged at the current price when renewing.