my windows 10 key has stopped working! wont re activate!

[syks]

so the guys that did my pc a while ago installed a fresh windows 10 pro onto my pc, it has been great for months but the other day I noticed a water mark in the bottom right telling me to activate windows, the key has stopped working and wont re activate!

I have bought another key but not sure if its just a case of going to settings, clicking on change key, entering the new key and then it all working? could someone please confirm that this will work

thanks

 

[syks]

its ok it worked