premium

As a noun premium

is bonus (extra amount of money given as a premium).

As an adjective freemium is

offering basic services for free while charging a premium for advanced or special features.

As nouns the difference between premium and superpremium

is that premium is bonus (extra amount of money given as a premium) while superpremium is a product or brand of very superior quality, better than premium.

As an adjective superpremium is

of very superior quality; much higher in price or value than a premium product.