Properly stored homemade Alfredo sauce will stay good in the fridge for up to 6 days.
Make sure to keep the homemade Alfredo Sauce sealed and in a jar with a lid to prevent any other food odors or other bacteria from potentially growing in it.
After 6 days in the fridge the homemade Alfredo Sauce will go bad and should be thrown out.
If you want to keep your homemade Alfredo Sauce longer than 6 days you can and should freeze it.
Homemade Alfredo Sauce will last for up to a year in the freezer but it's better to eat the Alfredo Sauce within 6 months so that it is at it's freshest.
I've kept homemade Alfredo Sauce in the freezer for a year in freezer bags and it was still safe to eat although it was not as good tasting.