Where did you pick that up? I **think** that the date on the bottle is the best before, which is three years after bottling.
I've got a couple of them in the cupboard that I brought back from their 'taproom' (pensioners tearoom in reality!) which I'm ageing for a while purely because I think St Bernardus Abt 12 is better based on drinking them both fresh. Maybe it'll change with age.
Personality I'd drink it now, but do a side by side tasting alongside St Bernardus. See what you think. If age it before you've even tried it you'll never appreciate the difference in future.
If you love it, Batch in Altrincham sell it, though it is about 20 quid a bottle. It's not worth that price imo when you can get St Bernardus for less than a quarter of the price.