One license gives you the right to install the program on up to three machines that you control, as long as these copies are not used at the same time.
The 'Yearly' license gives you the right to use the latest version of the program during one year. If you prefer to purchase the program, your license ('One-Off') will come with a 12-month free upgrade plan. The One-Off license covers all versions during the upgrade plan then remains valid without limitation on the latest version released before the end of the plan. Of course, if you own a One-Off license and wish a new version of the software after your plan has expired, you will have the opportunity to upgrade at a discounted price and this will renew your plan for a year.