  The CUPID-Mo experiment to search for 0$\nu\beta\beta$ decay in $^{100}$Mo
has been recently completed after about 1.5 years of operation at Laboratoire
Souterrain de Modane (France). It served as a demonstrator for CUPID, a next
generation 0$\nu\beta\beta$ decay experiment. CUPID-Mo was comprised of 20
enriched Li$_2$$^{100}$MoO$_4$ scintillating calorimeters, each with a mass of
$\sim$ 0.2 kg, operated at $\sim$20 mK. We present here the final analysis with
the full exposure of CUPID-Mo ($^{100}$Mo exposure of 1.47 kg$\times$yr) used
to search for lepton number violation via 0$\nu\beta\beta$ decay. We report on
various analysis improvements since the previous result on a subset of data,
reprocessing all data with these new techniques. We observe zero events in the
region of interest and set a new limit on the $^{100}$Mo 0$\nu\beta\beta$ decay
half-life of $T^{0\nu}_{1/2} > 1.8 \times 10^{24}$ year (stat.+syst.) at 90%
CI. Under the light Majorana neutrino exchange mechanism this corresponds to an
effective Majorana neutrino mass of $\left<m_{\beta \beta}\right> <
(0.28$--$0.49)$ eV, dependent upon the nuclear matrix element utilized.
