You can leave it connected. But,,,, if you don't ride daily then you will want to either disconnect, or at least switch off the controller while parked for a week. If longer than a week, definitely disconnect the controller even if switched off.
Beats me why the resistor hasn't become standard equipment on Ebikes yet.
THE LIPO RULES. NEVER ABOVE 4.3V NEVER BELOW 2.7V DON'T PUNCTURE
Ideal charging /discharging range for Lipo, 3.65v minimum 4.1v maximum
See battery technology section, FAQ thread at the top of the page for lipo noob info.