License key is cached for 1 week for performance reason. So it will be updated within 1 week. If you want now, You can go to Front End PM PRO > Settings > Licenses and remove your license key then save changes and again input your license key and again save changes.
I understand your concern. But please make a simple calculation, i charge 50 USD per hour. This plugin license fee is not even my one hour charge. Again i have to spend for this website maintenance. I believe you understand.