In the (new) gTLD program the registries often decide that certain terms or names are to be considered premium. In short this means that popular terms will be more expensive to register than less popular terms.
During the order or transfer process our system will warn you about these higher prices, asking you to confirm that you are aware of the higher price before the registration / transfer can be placed.
Depending on the extension, the domain's renewal may be at the premium fee again, or at the regular registration fee. The extension details pages in this knowledge base show this information for all extensions.