Activation of Dell Vostro 3555 Laptop: Windows 7 Professional x64, Invalid Key from Sticker

Hello!

DELL Vostro 3555 laptop


I decided to format the laptop that was bought as "used", of course I got it cleaned from the files of the previous user, but the time has come to carry out the next format.

The seller ran the company and I am not 100% sure if the "collective" license was not used for this laptop.

The laptop has a sticker with a license key on the cover.

To the point:

I installed Windows 7 Professional (it was a copy or actually a packet of various windows 7, because the seller did not attach any CD, etc.) from a bot-oval flash drive, previously cleaning all drives (C also). After completing the installation process, I entered the key from the sticker and it happened what usually happens "The entered Windows 7 product key is invalid for activation". I've seen quite a few of these problems on Google, but nowhere have I found solutions for DELL.


The easiest solution they suggest is to contact MS, but before making a phone call I'd like to know:
-What can such activation look like?
-Is it enough for the same laptop sticker, or maybe you will need something more e.g. a disc (which I do not have)?
-Can they stick to the source from which I got Windows 7?
-What to do if I used the activator in the hope that this would eliminate the problem?

A message is displayed in the attachment.

And the sticker is definitely for Windows 7 Pro, not HP? By installing the sticker version, you can activate the system by phone.
Activator use is piracy.
The data provided during the conversation (with the machine) is confidential and will not be used against you (from what I remember the last time I did it).
You will be asked for a code from the sticker and you will receive a code to enter.

The sticker is for Windows 7 Pro OA or OEM only the question whether in this case I can use the same key a second time

If you get through the phone and don't get it wrong, why not?

And such a question, just installing a copy of the system is not punishable up to 30 days to try it? Then if I don't give my key, they can "break"

Most of the codes entered from stickers for other manufacturers (such as DELL) do not activate automatically. Phone activation in this case almost always passes. You don't talk to a living person, just a machine.

Thank you very much 5 minutes and sweeping.