AirDroid Personal Edition (Green) and AirDroid Business Edition (Blue) are two products for different needs and usage scenarios. Since these are two different products, they are not interconnected to each other. If you are using a Personal version account, including the Personal free version (Basic account), or the personal paid version (Premium account), you cannot change your account to a Business account through upgrading.
Likewise, if you are currently an AirDroid Business account owner, you can pay the account difference and upgrade to a different Business plan, but you cannot switch to a personal version product.
If you would like more information on the differences between the AirDroid Personal and AirDroid Business, please refer to this article: