Ubisoft verification

Short question. Did I have a product if I clicked the button with Ubisoft account connection? After doing that the site shows me an activation key. Normally I would check that on Ubisoft app, but at that moment I don't have my PC, because it's dead, and I can't check it.
So, this key is just for letting me know what key was used, or I must copy it in Ubisoft app?
I don't know if there is any time limit for which I have to use the key.