Battery Problem

[MyDaughtersLS430]

New to us 2002 LS 430 (was given as a gift so my daughter would have a car). So, the previous owner mentioned the battery issue and just bought a battery with a 6-year warranty. Since my daughter is only learning to drive and doesn't plan to use the car often for at lease 6 months, what does disengaging the Smart Key feature actually change about the interaction with the vehicle? Would starting the car every 2-3 days eliminate the issue, or would the car need to be taken out on the road for a period of time? TIA 

Side note - even at nearly 22 years old this car is nicer than any vehicle I have owned lol 90k miles, all records and doesn't look like any seats, besides the drivers, were used.