Yes, you can change your plan at any time. If you change to a higher level during the term (e.g. change from Basic to Business), you will receive an invoice for the additional difference (daily billing). However, you are not entitled to a (pro-rata) refund if you switch to a lower level during the term (e.g. switch from Basic to Free). At the end of the term, you can switch to a lower or higher level. The price for your newly selected level will then apply for the new term.