Last time I looked into it, the license was good for the current major version.   So presumabably, if version 8.0 comes out youd need another license if you wanted to use the newt version or you could stick with 7.x as lomg as you can. The license may have changed since then, it is best to contact them by clicking the link at the top of the pricing page. Ive usually got a response within a day or two.