Q: Can you enable Query Store for a read-only replica?
A: No. Because the replica is read-only, and Query Store inherently writes data TO the database, you cannot enable it to capture queries that are executed against that read-only copy. I did create a Connect item for this request. If this is of interest to you, please up-vote it: Enable Query Store for collection on a read-only replica in an Availability Group. The more votes this has, the better the possibility that Microsoft will implement it, so feel free to share with your friends and have them vote too!
Read on for more questions and answers, and if you’re interested in it, vote on the Connect item above.