Windows to Go is only available on the ENTERPRISE version of W8 so it's already "Multiple Activation" Licences.
If the Windows to Go is loaded on to different hardware it *might* ask for reactivation but I doubt it. -- However if you add products like Office 2013 to a Windows to go system you could run into problems with THOSE programs trying to activate.
I've loaded a W8 to go system on to a Sony VAIO and an Acer Aspire laptop -- no activation requests. The hardware is different - W8 to go will get the new drivers first time from the Internet. After that the drivers remain in the system so you can re-boot in this case from the USB device ( I use a partition on a USB3 external disk) without windows looking for them again on EITHER laptop.
Whether the Enterprise system is "activating in silent mode" I don't know but I haven't had any trouble with it.
Office wanted re-activation though on the second computer. I got round that problem (LEGALLY) by installing Office enterprise 2007 --also multiple activation. Seems that Enterprise version of office 2010 / 2013 isn't on technet and you have to manually activate it.
While "Windows To Go" is available only in Windows 8 Enterprise, you will still be able to create a "Windows To Go" in Windows 7 and Windows 8 using the method in the tutorial below instead.
Windows 8 To Go - Setup on a USB Flash Drive or USB Disk
To activate Windows 8 Enterprise, you could use either option in the tutorial below to change/enter the product key number to have it activated afterwards.
Windows To Go - Create in Windows 8 Enterprise
Hope this helps.