There are two possible ways to upgrade your membership, depending on whether you have an individual account or your account has been provided by an organisation:
Individual account
You can upgrade your membership from your Plus account. Go to My account > Account, and click on Upgrade my account. This will take you to our membership page, where you can see what each membership level means. You can then upgrade your account by clicking the button Get started in any of the options.
Account provided by an organisation
If your membership has been provided by your organisation (clinic, university, member organisation, etc.), go to My account > Account, and click on the Upgrade to Pro button. This will take you to the checkout page, where you can upgrade to Pro membership.