If you were on the old pricing and you want to switch to the new Professional and Scale plans, these are the steps that you should take:
change the email address of your current account to email+old@yourdomain.com
create a new account with your email email@yourdomain.com
buy the new Professional plan
transfer your projects from your old account to the new one
get in touch with us to refund the remaining credit of your old account
As in the previous model you could have multiple billing accounts per project we cannot transfer the credits automatically, so we'll need to go through this process.
If you have any doubts don't hesitate to be in touch with our support.