Crypton Vocaloids’ voice can be used for commercial use. So, you can sell albums that used their voices for example.
However, you cannot use their character, visual avatar, to make mass produced goods and sell them. For that you need their permission.
Most of other companies Vocaloids follow these rules as well expect some expectations: fukase. To even sell albums that used Vocaloid fukase, you need his company’s permission.
Each Vocaloid’s TOS can differ slightly, so I suggest reading it before make purchase (especially if you’re producer) but generally speaking you can use their voices as you like (as long as not illegal of course) but their character usage is often limited that you can’t use them commercially.
