Is App Store Price one time, monthly, or annual?

How can I tell if the price shown for an app in the App Store is one time, monthly, or annual?

For example: the Guitar Tab Maker app has a price button of $5.99. So I must ask is that $5.99 a one-time fee, a monthly fee, or is it an annual fee? It does make a difference in determining the overall cost, wouldn't you agree? Shouldn't that information be readily available to all potential buyers?