This is incorrect Bill. The perpetual is a permanent license. Failing to renew will prevent you from moving to the next major version (i.e. 8), and the loss of the support portal, but will not revert to the OSE.
Effictively you have thirty days garce period for renewal then it becoes an 'Open Source' version, as you've already mentioned the NE feature stop working.
We purchased such a license for this very reason.
Ben Franklin quote:
"Those who would give up Essential Liberty to purchase a little Temporary Safety, deserve neither Liberty nor Safety."