Cubase 7 Artist with Full Cubase 7 trial problem

I have just purchased Cubase 7 Artist which has the option of Full Cubase 7 trial for 25 hours. I want open a project and bounce down multiple stems at once (which only the full trial version can do ive now found out!) but because ive opened both versions it no longer gives me the option to continue with trial version at the start and can’t find it anywhere. A pretty lame problem i know but appreciate some help, thanks