How do I make sure I'm not showing retargeting ads to people who already came back and completed their purchase?

I've been running Meta ads for my Shopify store, and I'm noticing something frustrating: I'm likely wasting ad budget retargeting customers who have already purchased from me. It's like throwing money out the window! Every time someone completes a purchase, I want to immediately remove them from my retargeting audience. My current setup means I'm potentially showing the same ads to people who've already converted, which not only wastes my ad spend but could also annoy customers who've just bought from me. I need a smarter way to manage my audiences that automatically updates in real-time. The last thing I want is to appear disorganized or waste precious marketing dollars chasing customers who are already in my ecosystem. This feels like a critical optimization that could save me hundreds, if not thousands, of dollars in unnecessary ad spend.