Hello. I bought some Aegean miles last year on 7 November 2018 (with bonus). Haven't used it since then.
From the FAQ
Do my Tier or Award miles expire?
Tier Miles have a twelve (12) month lifetime. Award miles do not expire and you may redeem them as long as your Miles+Bonus account remains active*.
When will these miles expire? So the next question how to keep my Miles + Bonus account remains active?
Thanks