how long is garlic infused oil good for? should i put in the frig.?

Chef June is right on target especially from a food safety issue. Garlic can be contaminanted and then when in is sitting in an oil enviornment all around it you could have potential foodborne illness problems. Stores in refrigerator for 5 to 7 days but no more than the 7 for sure.

Yes, please refrigerate any suspension of garlic in oil, including vinaigrettes. They don't keep as long as you think. I toss them after a week.

http://www.food52.com/foodpickle/5286-how-long-can-i-store-homemade-garlic-infused-olive-oil