I need help with a question about pumped milk!

Question! My LO currently has a cold and his nose is stuffy so it's hard to breastfeed. I have a few oz in the fridge and my question is this : when I take the oz I have in the fridge and warm it up (while putting the bottle in warm/hot water) IF LO wakes up and just goes back to sleep without touching the milk can I then freeze it? Put it back in fridge? And if yes how long will it keep? Thank you in advance! I really appreciate you taking the time and replying!