I bought a can of pesto and truffles. It says to use within 3 days of opening. I'm wondering if I can freeze it since I doubt I will use it a

I have frozen pesto and many other similar items and they freeze well and defrost fine, so I'd say go for it! Just remember when defrosting that you will want to leave time to let it defrost naturally because if you heat it, the cheese will melt and this could be undesirable.