the generac mobile link unit has a YEARLY cost of $49 for use, plus the price of the unit and install (the newer generators with evolution 2 controllers have the units built in).
my Genmon unit has no monthly fees. only cost of unit.
i like mine because i travel alot, or are away from home. i get instant alerts as to status of my generator. if im away and power is out for long time, i can alert a friend to go check the unit. now if your home, dont bother.
the basic FREE mobil link service just gets you a monthly email report.
the pay one gets you instant (or so they say) text or email, plus you can set exercise time, etc from the app. thats about it.
my Genmon gives me alot more info, such as propane tank levels, power output, utility and generator power levels, battery levels, frequency and rpm of engine. plus it instantly emails me if the generator has a yellow or red alert light show up. it texts me whenever it exercises.