Connecting your accounts before you logged in with Google Drive
From your MindMeister Dashboard, click on the Avatar icon in the top right and select My account.
Select the Me option from the right side menu and access the Connected accounts tab.
You will be able to connect your Google account to your MeisterLabs account from here:
Connecting your accounts after you logged in with Google Drive
If you already accessed MindMeister via Google Drive and you were using another email address in your MindMeister account than your Google email address a new account was created. You didn't lose your mind maps or subscription.
You will need to disconnect your Google account from the second account that was created and then just follow the steps mentioned above in your main MindMeister account.
To disconnect your Google account:
1. Click on the Avatar icon in the top right and select My account.
2. Select the Me option from the right side menu and access the Connected accounts tab.
3. Click on Configure then click on Disconnect button.