This term is trying to be clever, it is the combination of two words: free and premium. What it means is that businesses are also trying to be clever, by giving you basic services or the base product model for free and then charging you for using its advanced functions.
For example…
A company that uses a freemium approach is MailChimp’s. The automated email marketing software company allows users to sign up to its basic account which allows up to two thousand subscribers and twelve thousand emails per month for free. To access more features, the users need to pay ten dollars per month and if you have more than two thousand subscribers, you pay thirty dollars a month.