Best way to upgrade 7 computers from Home Premium to Pro?

I have become confused reading the various licensing situations so forgive me for posting what may have been asked before.

I volunteer at a local senior center where we have 7 computers running Windows 7 Home Premium.

6 of them have identical hardware. These all have validly purchased licenses.

For various reasons, we want to upgrade to Professional (to use the security policies, etc.).

I thought we could purchase the Anytime Upgrade license for each one, and then just perform the upgrade on one of them. Then when finished, we could make an image and install that image on the other identical machines and change the product key to the Anytime Upgrade key we buy for them.

But upon reading the various tutorials here, I think the Upgrade license will only be accepted when we actually do the upgrade, so it probably won't work to change it on an image.

Can someone help clarify this and what the best way to do this might be?

I think you will probably have to do each one. A few years since I did mine but I memory serves it only takes a few minutes as the new key only allows the extra system options to be added to the existing OS.
Art.

It's actually a bit more complicated.

We have to re-install the original software because the site became infected with some viruses.

So there's a lot of Windows Updates to perform, etc.

There are no longer any Windows 7 Pro licenses being sold, so we have to do the Anytime Upgrade.

Perhaps do one clean image / clone of premium and activate it on each machine. Then do the individual upgrade to pro.

Art.

That sounds like a good plan. Thanks.
I'll leave this open for a bit in case there are other replies, then mark as solved when I try it on Monday.

Professional is still available, regularly goes down to $130 on TigerDirect.com.

You'd want to install with the underlying Home Premium license, then insert Anytime Upgrade key to unlock the few extra (expensive) features in Pro which almost no consumers need. Windows Anytime Upgrade - How to

Since its the same hardware you should be able to then image the finished setup and apply the image to the other PC's. If this fails for some reason (SID, HID conflict perhaps) then refer to Windows 7 Installation - Transfer to a New Computer whose author will gladly help you in Comments section.

Using Audit Mode possibly for this purpose is discussed in this recent thread: Fresh install of Win7Pro using OEM disk but Anytime Upgrade Key

Thanks, I don't know how I missed the TigerDirect. But at any rate, the Anytime Upgrade is a bit cheaper and we have practically no budget for this as it is.

I did read those other tutorials and one seemed to indicate that you can't use sysprep with anytime upgrade. That's what confused me. I thought that the only way to enter the Anytime Upgrade key was to perform an upgrade, not change a product key from another image.

The main reason we want to use the Pro version is because we got these viruses and all our users are using Guest accounts. We do use Security Essentials and MalwareBytes and some other browser filters.

We don't understand the restrictions and rules of that account, so we thought we'd use the local security policy to make standard user accounts with restrictions we specify.

Anyway, thanks for the helpful advice and great tutorials. I think we can muddle through this.

Wow, 150 updates from Windows 7 to Windows SP1 then another hundred plus to get it current.
6 hours of downloads.
Still working on the first computer....

At least the Anytime Upgrade worked very easily...

We solved this fairly easily.

We upgraded one machine fully and saved the image.

We ran the Anytime Upgrade of the remaining machines to the point where we had a new key.

Then we restored those other machines from that one image and changed the product key.