Yes. At etruel.com you can upgrade your current license, for example to more websites or to a bigger bundle, without buying a new license from scratch. You keep the investment you already made.
Log in to your account and click Licenses. Click View Upgrades below the license you want to upgrade.

If your license has expired, you see Renew to upgrade instead: renew it first. See How do I renew an existing license key?
It depends on the license you choose. The list of upgrades shows each option with its cost and its expiration date. In most cases an upgrade costs less than buying the new license separately. Click Upgrade License next to the one you want.

You add products or websites to the license you already have, and you keep your previous investment. It’s easier than starting over with a new purchase.