The access tokens you generate using the generateToken API are valid for 6 months. When they expire, you can use the refreshToken API to get a new access token. The refreshToken API requires a "refresh token" that was given to you in the original generateToken API call. If you don't have that refresh token, you should use the generateToken API to get a new access token.
Note: We recommend you use the refreshToken API to get new access tokens when they expire. You DO NOT need to generate a new access token before 6 months.
To request an upgrade, login to your account on the developer portal, and click on 'Account' (under your email address on the top right corner), and then click on 'Upgrade Plan'. After filling out the form with the required information, click 'Submit'. Our operations team will get back to you after reviewing the request.