I have an open-source developer licence for Intel ifort/mkl/cluster/icc which expired on July 11th 2019. The moment it expired I could no longer use ifort or other compilers, even though they were downloaded way before the expiration date. I am not sure if this is a feature (Bug) in the Flex licence structure; there is a small chance that it is OS related since we updated everything about three months ago -- but the timing does not work.
N.B., I have twice applied to renew my open-source developer licence and have had no response even though the processing is supposed to only take a couple of days -- it was never this slow before.
I think the way Intel handles the free licenses is that they have a hard expiration date and you need to renew them. Yes, the renewal process is clumsy and, if what I remember is still the case, is usually handled by a single person in the marketing department.
My advice is to file a "bug report" for any issue related to licensing - that way it will get tracked and a support engineer will make sure it is followed up.