If your Division Order arrived before your Lease Expiration Date, it is possible that that was information to you that your property was pooled with other leases into a larger Unit. That Unit MAY have seen activities, which would keep your lease active beyond its primary term.
Check, by calling the company that send you the Division Order.
Lucky you. A division order is the first step in getting paid production royalties. The operator (lessee) has checked title and operating agreements and put you in line for payment. Check and understand everything on the DO. It is unique to you. Confirm the decimal share. That will show up on every check you receive. The decimal shares all add together to 100% or 1.000000 of the distribution of well revenue from sales.