What happens when you over deploy from SEPM?

I currently have 2 seats available of a total of 260 in SEPM.  I have been trying to renew one of my licenes with my distributer for 2 weeks now but the process is painfully slow.

I want to know what happens if the licence (of 15 seats) expires before I manage to renew it?

I can see an "Overdeployed" seciton in the licence summary so I'm hoping that there's a period where they allow you to keep running!