  M51 ULX7 is among a small group of known ultraluminous X-ray pulsars (ULXP).
The neutron star powering the source has a spin period of 2.8s, orbits its
companion star with a period of 2 days, and a super-orbital period of 38 days
is evident in its X-ray lightcurve. Here we present NuSTAR and XMM-Newton data
on the source from 2019 obtained when the source was near its peak brightness.
We detect the pulsations, having spun up at a rate of 3$\pm0.5\times10^{-10}$ s
s$^{-1}$ since they were previously detected in 2018. The data also provide the
first high-quality broadband spectrum of the source. We find it to be very
similar to that of other ULXPs, with two disk-like components, and a high
energy tail. When combined with XMM-Newton data obtained in 2018, we explore
the evolution of the spectral components with super-orbital phase, finding that
the luminosity of the hotter component drives the super-orbital flux
modulation. The inclination the disk components appear to change with phase,
which may support the idea that these super-orbital periods are caused by disk
precession. We also reexamine the super-orbital period with 3 years of
Swift/XRT monitoring, finding that the period is variable, increasing from
38.2$\pm0.5$ days in 2018--2019 to 44.2$\pm0.9$ days in 2020--2021, which rules
out alternative explanations for the super-orbital period.
