You should have received an email as soon as there was a licensing issue as mentioned in the below kbase article.
" When out of compliance, due to expiration of licenses or insufficient device counts, you will be notified by e-mail. "
I know these are working because I received an email for an insight Trial I had on one of my networks.
I'm with Blake here. You receive a warning well before the org expires. And even then a grace period is started. During that period you will receive lots of emails warning you. Only after all that you get disabled.
Are you on co-termination or per device licensing?