Curve black... is there a 12 month commitment or anything like that?

Looking to upgrade to Curve Black mainly for the travel insurance. I see that it’s advertised as £9.99/month however I’m wondering if there’s any sort of commitment for this plan… e.g. 12 months?!

If not, then is it possible to upgrade to Curve Black for say 2-3 months so that I have the travel insurance, and then downgrade back to Curve Blue (for free)?