Ace's Rewards offers four distinct kinds of prizes that vary in the number of bits that they give, based on your wagering activities.
To answer the question that brought you to this article, yes, rakeback bits do expire if they are left unclaimed for a set amount of time.
Let's dive deeper into this, shall we?
Instant Bits - Instant bits can be accumulated for as long as you want, without the fear of them expiring.
Daily Bits - Daily Rakeback expires every day at 00:00 UTC, just as the new batch of daily Rakeback becomes available.
Weekly Bits - Weekly Bits expire every Monday at 00:00 UTC, meaning you have an entire week after their availability, to claim them before they expire.
Monthly Bits - When it comes to Monthly Bits, they expire on the first of the month at 00:00 UTC, which indicates that you have a whopping 30 days before they expire, never to be seen again.