The title of the question is probably specific enough, but I'll give more color anyway.
Here's a quick timeline.
- I received output A a year ago.
- In the last year, output A has been a decoy in 3 transactions.
- Today, I spend output A; therefore the key image ensures the output can't be spent again.
Question: In the future, can output A be used as a decoy again?
Bonus question: Is there a limit to how many times an output can be a decoy in a ring signature?