“Cognac does not age in the bottle, so however old it was at the time of bottling (and VSOP indicates at least four years) it is still that age for aging purposes.

If your only concern is whether it is still good, an unopened bottle of Cognac can stay good for much longer than 13 years. I would think it should be fine. The things to look for that would be a matter of concern, would be leakage through the seal or excessive evaporation (i.e. low bottle fill). If you don't see that, I would guess it's fine.”