Lewis & Short

2. perpĕtŭo, āvi, ātum (old perf. subj. perpetuassint, Enn. Ann. 322), 1, v. a. [perpetuus], to cause a thing to continue uninterruptedly, to proceed with continually, to make perpetual, perpetuate (rare but class.): libertatem ut perpetuassint, Enn. ap. Non. 150, 30 (Ann. v. 322 Vahl.): amator qui perpetuat data, Plaut. Ps. 1, 3, 72: ut si cui sit infinitus spiritus datus, tamen eum perpetuare verba nolimus, Cic. de Or. 3, 46, 181: judicum potestatem perpetuandamputavit, id. Sull. 22, 64: di te perpetuent, may the gods preserve you! a form of salutation addressed to the emperors, Lampr. Alex. Sev. 6.