Sounds like some little confusion here. There are two products: Logic Pro and Logic Express.
Logic Express doesn't need an xskey but Logic Pro does. If you've bought a kosher copy of Logic Express, it should quite happily install and run standalone. If you've bought a Logic Express upgrade, you'll need to have Logic Express 6 on the computer before Logic Express 7 will install. Same for other variants of Logic Express 7 (7.1 and 7.2).
Logic Pro is a substantially more expensive product ($1,000) and is protected by an xskey. If you've bought a kosher Logic Pro 7, it will have an xskey included, whether it's a fresh copy or an upgrade.
Best check exactly what you have and come back to us.
Pete