This trick only work in latest version (7.2+)
1. Go to Front End PM PRO > Settings > Licenses
2. Input your license and save
3. in address bar add &input_license_data=front_end_pm_pro end of your url
4. press Enter
5. a new text box will show under license input field. Click Get Data bottom of that field.
6. copy that data and paste in that input field. Then save.