The principles of Freemium
Companies are always exploring new ways to increase customers while keeping down cost. The freemium model solves this by letting you showcase your great product with minimal expense but maximum value.
Generally, your freemium offer will be a cut-down version of whatever it is you sell or do.
A mobile phone app with some of the functionality locked out, or a financial consultant offering a free 30-minute consultation over Zoom would both qualify as a 'freemium offer'.
Freemium adds immediate value to your customer's buying experience with minimal disruption to your business.