Vertigraph offers perpetual licenses for BidScreen XL ($799) and SiteWorx/OS ($2,999). After the initial purchase, the seat keeps working forever — even if Full Serve maintenance lapses.
Most takeoff vendors retired perpetual in favor of subscription-only over the last 5 years. PlanSwift, On-Screen Takeoff, ProEst, Procore, and others moved to subscription. Bluebeam went subscription with Revu 21. Vertigraph and AGTEK still offer perpetual licenses.
Total cost of ownership over 5+ years usually favors perpetual when both options exist. A $799 perpetual + $199/yr Full Serve for 5 years = $1,595; a $1,749/yr subscription over the same period = $8,745.