This is an old topic but unbelivably comes online once in a while.
XPe devs should understand the difference between runtime licenses and licensed XPe Toolkit.
Runtime license is provided to you after you signed a legal agreement with Microsoft (through XPe distributor) called CLA. Then you are given stickers with PID numbers on it (numbers like xxxxx-xxxxx-xxxxx-xxxxx-xxxxx). Used to be that the stickers all had different unique PIDs, nowadays they are the same in one multiple-license volume purchase. Depending on how many licenses are covered by your agreement you should be getting some amount of stickers. You use just one PID from any sticker and type it in the Runtime ID field on Configuration Settings page in TD. This will get rid of the "Evaluation build ..." text at run time (it other words, your runtime will be properly activated).
Another story with the toolkit. To be able to create activated runtimes, to even see that Runtime ID field in TD, you must be having and using the licensed toolkit. In Eval toolkit (the one you can download from public MSDN or receive on Eval CDs) that field is hidden, thus not allowing you to create activated runtimes. The CD-key you are getting from Microsoft (aka the toolkit Serial Number) is to be used once when you are installing the tools (TD, CD, database, etc.). Don't put this number in the Runtime field in TD - it is a wrong place for it. Rather type in there a PID from a sticker.
Also, just FYI. In SP2 times there was a QFE issued by Microsoft that was patching the toolkit to be able to use new PID range in SP1 database. That QFE was to address Extend Runtime Product Key Range for Windows XP Embedded. Quote: "This update allows OEM's and embedded developers to use runtime product keys provided after the release Windows XP Embedded with Service Pack 2 on a database containing Windows XP Embedded Service Pack 1 or earlier component databases.".
If you contact your XPe distributor, they should be able to explain you all the details about PId and etc.