Hello,

The eligibilty criteria of NMAT only says that you should have a minimum of graduation degree of 3 years or more then you are eligible to give NMAT exam. Having one year drop will not create any difficulty for you while giving exam or while taking admission.

You will just have to prepare your justification for that year gap with legitimate reason, if you are able to do so you will not face any difficulty at anywhere.

Hope this helps!