Is there a maximum number of devices allowed on a Google Play Account?

Many schools are looking at using Android tablets in classrooms. Some have classroom sets of 35-40 tablets. As a means to manage apps, having them tied to a single Google Play account would be ideal. Is there a maximum number of devices allowed? This setup would also be cost effective, if the school uses any pay apps, as the app is linked to the account, not the devices. Does anybody have any experience or knowledge beyond, "I have 5 devices in my family all synced and it works."?