Upgrading backup exec 2010 r2 to 2010 r3

Hi, i'm looking at upgrading one of our customers backup exec to 2010 r3. is it ok to use the ISO from the trailware site? or will this just install the trial?

They currently use backup exec 2010 r2 and are fully licenced.

Any help is appreciated as they havn't had a good backup for near a month now!

Thanks