If you are getting notifications from FeaturePremium, then your Mac is infected with adware. FeaturePremium is adware for Mac.
FeaturePremium changes setting in your Mac. First, FeaturePremium installs a browser extension in your browser. Then, after FeaturePremium hijacks your browser, it modifies settings in the browser. For example, it changes the default home page, modifies search results, and displays unwanted pop-ups in your browser.