For any of the reputable hotel chains, if you had attached your membership number to the booking there are 3 places to look, after checking out, whether the number was correctly recorded:

1. On the E Mail confirmation it will show your name and number
2. On the hotel bill it will show your name and number
3. You can log in and view your "stay history" for the last few stays

Now, which if any of these is available for A-Club?

AFAIK the only hint of a feature was found by starflyergold in the cancel-booking page where you can get a list of your upcoming stays.

Would be nice when running the gauntlet of the A-Club service desk to be able to prove that your number had indeed been attached to the booking and it's entirely their fault that the nights didn't post.