Hi Air_China
I'm not with Laminar Research, just a fellow simmer in the UK.
The digital download 'demo' version of XP11 is more or less exactly the same as the fully licenced version, although there may be one or two restrictions.
One of these restriction could be that you can only use the default LR aircraft in the 'demo' version and have to pay for the licenced version of XP11 before you can use addon aircraft.
I don't know this for certain, but it sounds logical to me!
Regards