You don`t buy a full version, you rent a Sibelius License for 1 year. After this you need to buy a new license to continue working with Sibelius Ultimate, which means that you do not own the software.
Sibelius is the world’s best-selling music notation software, offering sophisticated, yet easy-to-use tools that are proven and trusted by composers, arrangers, publishers, educators, and students alike. And with the new Sibelius, you'll be able to access the software in more affordable ways than ever. Compose with a low-cost subscription. Own the software outright. Manage multiple copies with Sibelius network licensing. Or get started with Sibelius | First. The choice is yours. And with the integrated Annotate feature, multi-touch gestures, Surface Pro 3 pen support, and more, Sibelius enables you to express your creativity in brand new ways, whether composing for a live performance, movie, television, media entertainment, or in the classroom.