  Moir\'{e} excitons (MXs) are electron-hole pairs localised by the periodic
(moir\'{e}) potential forming in two-dimensional heterostructures (HSs). MXs
can be exploited, $e.g.$, for creating nanoscale-ordered quantum emitters and
achieving or probing strongly correlated electronic phases at relatively high
temperatures. Here, we studied the exciton properties of a WSe$_2$/MoSe$_2$ HS
from $T$=6 K to room temperature using time-resolved and continuous-wave
micro-photoluminescence, also under magnetic field. The exciton dynamics and
emission lineshape evolution with temperature show clear signatures that MXs
de-trap from the moir\'{e} potential and turn into free interlayer excitons
(IXs) at $T\gtrsim$120 K. The MX-to-IX transition is also apparent from the
exciton magnetic moment reversing its sign when the moir\'{e} potential is not
capable to localise excitons at elevated temperatures. Concomitantly, the
exciton formation and decay times reduce drastically. Thus, our findings
establish the conditions for a truly confined nature of the exciton states in a
moir\'{e} superlattice with increasing temperature.
