Is there a way to activate Windows 7 when it's saying my license code is already in use?

Are you certain you're using the right key?

A lot of times, the key that was used to install Windows in the factory is a bulk-license key; your individual product key is on a sticker. If you used a tool to extract your product key before the reinstall, it won't be the right one. That might explain why Microsoft sent you back to your OEM: because the key you gave them came up as OEM-use only.

Windows requires you to activate your copy by providing a valid product key within 30 days ^[1]. Aside from volume licensing, the product key is typically only valid on a single computer.

As it seems the key you received is already registered by some other party, I'd suggest taking your issue back to the aforementioned "licensed source" and getting a working product key.

You should also make sure that the security features of the packaging are ok. I'm not aware of other parties selling plain product keys online, except for Microsoft, and even then you'd get a Certificates of Authenticity (CoA) with your product key card.

If it seems that the key you received is a counterfeit you should report the seller to Microsoft.

You don't need to buy the Acer technical support at all. The cost and P&P of the factory recovery disks is all you need. Once you receive the disks the key will already be activated as these are the recovery disks you should have made the moment you received the computer.

I've done this numerous times for customers who neglect to make their own set of recovery media.

All you need is the device serial number, model, payment and an address. The disks can take a couple of weeks to deliver, however.

To be brutally honest, there is NO excuse people should not make their own recovery disks.

The Windows you purchased from that "licensed source" isn't legitimate and is most likely counterfeit and sells the same (already used key) again and again, so you got scammed.

Now, you shouldn't need to buy a Windows as your computer already has a license sticker on it with a product key. You can just download a clean ISO corresponding to that license, either on MSDN (if you have a subscription), on forum posts like these which list direct (legal) download links to a Microsoft distributor or on some shady pirate sites (make sure to check the hash against the official hashes published on MSDN to make sure you didn't get a compromised image).

Once you have that ISO you can reinstall it and enter the product key from the license sticker and it should be good; it won't activate right away and ask you to activate by phone but phone activation will work just fine.

You don't need to activate Windows (at least in Windows 7). But neither do you need to make use of any cracks, or doubtful software, or loaders.

There is a quite simple, easy solution. No software involved. If you have the Product Key, you can rearm - i.e. reset the rearm count. You reset your rearm count (back to 4) how ever many times you want, so you will have Windows 7 running forever in trial mode.

Note: the PRODUCT KEY is all you need, not any activation code - there is no need to phone Micro$oft.

There is no tampering with O/S files, so no breach of the licence terms.

1) Stop the Software Protection service sppsvc. Go to Start > Run; open services.msc; go to the "Software Protection" service, right click on Software Protection, select Stop.

2) Move the file tokens.dat to your desktop :

Find C:\Windows\ServiceProfiles\NetworkService\AppData\ Roaming\Microsoft\SoftwareProtectionPlatform\tokens.dat

Right-click it, CUT it, and paste it onto the desktop. Move it, don't copy it.

You may need to take ownership of the file in order to move it.

3) Go to C:\Windows\System32

Locate 2 hidden files with this extention: ".C7483456-A289-439d-8115-601632D005A0" Move the two files to the desktop. Move them, don't copy them.

You may need to take ownership of the files in order to move them. They are HIDDEN files - make sure, in "folder options", that you can see hidden and system files.

4) Start the Software Protection service - sppsvc (open services.msc , look for "Software Protection" service, right click on it, select Start).

5) Open a command prompt as administrator, and run this command: slmgr -dlv

6) Stop the Software Protection service.

7) Put the three files you moved to desktop back in their original locations.

8) Install your product key. Open a command prompt as administrator, and run:

slmgr /ipk XXXXX-XXXXX-XXXXX-XXXXX-XXXXX

[change "XXXXX-XXXXX-XXXXX-XXXXX-XXXXX" to your actual product key]

9) Reboot your computer.

10) Run slmgr -dlv again, and you will see that re-arm has been reset.

My tip: if necessary, go through this procedure twice, because results from it will change once the product key is entered on the system. Typically, on the second run through you may need only to do steps 1 to 6.

I have only tried this with Windows 7.