1) Not only can you — you should!
2) WordPress Multisite works best on a VPS (or dedicated server), where the site administrator has full control over web server configuration and other environmental factors.
3) Also, the nature of a blog network, which contains many sites run by many different people, makes it somewhat difficult to predict things like traffic and resource usage. A scalable, or cloud-based, VPS plan will help you keep your network stable and running.
