In late August, a new and improved activation process for Office client (aka Office Pro Plus or Office Click to Run) will be deployed.
This new process will simplify the activation by automatically using the user’s credential to perform the activation (if single sign-on is enabled).
It will also simplify the process if you have activated Office on more than 5 devices; the process will automatically pick the least recently used device to deactivate it and allow the activation on the new client; no more need to uninstall Office. There is no change in regard of the number of device you can activate Office – this is still 5 devices