Our customer is facing problem

Our customer have implemented this On premise edition, now there is a bug stating that after they've updated the license file with 8 users license and it will automatically revert back to the FREE EDITION 3 users after they use it for 3-4 days, and it will automatically deactivated other users and remain 3 users available. It kepts repeated for 4 times each time I've update the license file that Adventnet provide to us. Hope you can reply to us ASAP. Thanks!

Edmund
Mediamix IT Solutions Sdn Bhd