No, hang on to those. If you even have to do a total reinstall - downloading a fresh ISO, you'll need the key. If anyone else is using it, you may find it's locked out forever.
However, the new 10's seem to arrive with a fresh key if BELARC is to be believed, so you might want to take the gamble to garner a few quid from the procedures.
On one install I did, nothing would allow the ISO download - until I tried the key that was on the side of my HP pc in the US. I just happened to have made a note of it when it was sold for a few dollars with no OS.