One subscription will suffice, since a MathType subscription includes a product key valid for MathType Desktop for Windows, Mac, and online use (Google Docs, Microsoft Office Online).
Do I need to buy two separate subscriptions? No. I have both Windows and Macintosh computers. Contact us for details on how to purchase a site license. Do you offer site licenses? Yes, we have community subscriptions for K-12 schools, university departments, university campuses, corporations and government organizations. Simply tick the Academic discount option in the purchase process. If a credit card is not a valid option for you contact us to arrange wire transfers and purchase orders as payment. What methods of payment are available? Supported credit cards: Visa, MasterCard and American Express.