They both revert to trial mode if I don't do a live update every time I launch the sim
That seems to indicate either you or another add-on must have set the sim in a wrong "Compatibility" mode, since the Live Update reset it to the correct value ( no Compatibility mode, that's the default the sim installs with ), that's why it gets fixed.
In some cases, even Windows itself might set a wrong compatibility mode automatically, either because an add-on started by the simulator requires it, or after a crash, Windows will try to help you running the program even if it wasn't required.
Running the sim in the wrong Compatibility mode will result in some performance loss ( video drivers will run in a reduced performance mode ) and issues with registry keys, since different registry root keys will be used, which will cause problem to many products, like reverting in Trial, which the Live Update fixes by resetting all compatibility modes to default.
The only compatibility mode that is safe to us is "run as adminstrator", that can be used or not, it won't make any difference to us, even if some add-ons requires it, so the Live Update won't remove it if it's enabled, even if it's not a default setting.