Please backup your website first.
Then check Dashboard > Front End PM PRO > Settings > General > Remove data on uninstall and save changes.
Then Go to Dashboard > Plugins page and uninstall and delete this plugin from there.
Then again install and activate this plugin following https://www.shamimsplugins.com/docs/front-end-pm-pro/getting-started-2/activate-pro-version/.
Let me know.