If you purchased a new Malwarebytes subscription, you can change the license key you are using in Malwarebytes for Mac. Changing your license key allows you to continue protecting your computer without deactivating your old license key first.
Change your license key
Open Malwarebytes for Mac.
Click My Account.
ClickChange License Key in the following window.
Enter your license key in the following window, then click Activate License.