Final Result of the MAJORANA DEMONSTRATOR's Search for Neutrinoless Double-$\beta$ Decay in ${}^{76}$Ge

The MAJORANA DEMONSTRATOR searched for neutrinoless double-$\beta$ decay ($0\nu \beta \beta$) of ${}^{76}$Ge using modular arrays of high-purity Ge detectors operated in vacuum cryostats in a low-background shield. The arrays operated with up to 40.4 kg of detectors (27.2 kg enriched to $\sim$88% in ${}^{76}$Ge). From these measurements, the DEMONSTRATOR has accumulated 64.5 kg yr of enriched active exposure. With a world-leading energy resolution of 2.52 keV FWHM at the 2039 keV $Q_{\beta \beta }$ (0.12%), we set a half-life limit of $0\nu \beta \beta$ in ${}^{76}$Ge at $T_{1\mathrm{/}2}>8.3\times {10}^{25}$ yr (90% C.L.). This provides a range of upper limits on $m_{\beta \beta }$ of $(113-269)$ meV (90% C.L.), depending on the choice of nuclear matrix elements.