Garlic infused oil can last up to about two years in the cupboard. That said, the flavour slowly fades over time, and the garlic taste won’t be as bold the longer it sits.
Honestly though, if it’s sitting in your cupboard that long, you’re probably not using it right. A good garlic oil shouldn’t last that long. It should be something you reach for all the time.
A simple trick is to add a splash to almost anything you’re cooking. It instantly boosts flavour and makes your meals taste more complete.