Office 365 Pro Plus

Hi Gideon, What kind of tablets are you using? If these are devices with Windows 10 installed, then activation should occur automatically when the device connects to the internet. If you want to prevent that users have to activate manually the first time they use the device then you should use an Office version that supports Key Management Services or ADDS. It is also possible to install O365 Proplus for large deployments using the Office Deployment Toolkit (ODT). You should enable shared activation then: https://technet.microsoft.com/en-us/library/dn782860.aspx