PC: Business rule BRF syntax condition question

I am in the middle of creating the Business Rule QM_EPR_01C1_01_Q which is about monitoring materials by expiration date.

What I would like to achieve is to be able to filter on products that are or will be expired in a few months time (field shelf life expiration date). BRF sounds like the logical solution

Any idea what syntax formula I need to setup to fulfil this requirement?

See attachment (syntax formula)

Thanks!