30 C.F.R. § 556.1100
How does a lease expire?
(a) Your oil and gas lease will automatically expire at the end of its primary term unless you have taken action, as set forth in § 556.601, to maintain the lease beyond the primary term.
(b) Your sulfur lease will automatically expire at the end of its primary term unless you have taken action, as set forth in § 556.603, to maintain the lease beyond the primary term.