I've read plenty of posts from members on various boards using AAS even 3 to 5 years with no noticeable difference in results. I think storing in a freezer is no better than a drawer in your bedroom. As long as the oil isn't rancid looking, I'd continue to use.
It might lose some potency over time due to the compounds starting to degrade.
@Liska Since you do a lot of testing, have you tested the same batch twice at different time points and did you notice a difference in concentration?