Looking at Intune subscriptions and its related features

It seems like you want a bit of MAM and MDM, it's best to completely manage the devices with MDM in my opinion. Are the devices BYOD or COD? Per licensed user you can have 15 devices registered. Licensing a user can be done manual or, if you have Azure AD Premium P1 and Azure AD Connect, by assinging Windows Active Directory Groups to that license. You can set the max amount of devices to one user if you want, that way you know that they can only use one device.

But without Azure AD Connect and syncing users, you will have users having a seperate account next to their Active Directory account with different passwords.. I wouldn't recommend it, running Azure AD Connect is free and will only cost you some server resources.