For company accounts: Yes, we want to be as flexible as possible to suit companies of all shapes and sizes. So you might have a monthly plan for 50 users and if you need to increase that to 100 users for the duration of a project or reduce it down when a project finishes, you can do that easily within the Proteus admin console.
If you want to upgrade from monthly to annual billing and get 2 months free, no problem. We cannot however provide refunds.
For freelancers: it’s all free for you unless you are operating as if you were a company (see What is the difference between a Company and a Freelancer?).