Yes! With the latest version of Balsamiq Wireframes for Google Drive, you have the ability to purchase a subscription for multiple people (we call these Editors).
After subscribing to the desired plan, there will be a section called Balsamiq Wireframes Editors on your billing page. That's where you will be able to add the Google email addresses of the people you wish to pay for. By adding them to your subscription, you are providing them with the ability to create and edit wireframes with the Balsamiq Wireframes for Google Drive app.
More details here: