Can someone tell me what that means?

Koiruus points out that ports made by members of the community have no Alien Dalvik on board due to licensing problem.
Only Jolla holds a license to ship their work with AD but can not grant it to 3rd parties. That is obviously due to myriad group not getting money because no one knows how many ports are out in the wild for example.

But we have a wording issue here.
Technically, jolla does "port" (verb) sfos to the Xperia device, eg. doing hardware adaption and such.
But (if confirmed via blog post) the result is not a Community Port (general name for devices ported by community) but a official Jolla release with all licensing Jolla can offer for own releases.

And to paint it black:

One possibillity still is, even if Jolla releases the image, we could end up with user flashable XX that does not contain AD due to forementioned licensing and tracebility problem to pay for all Dalviks in use by selfporters.

Thats why i strongly hope jolla will not offer the port for free because it will propably lack AD in that case (speculation alert).

Edit, to make it clearer, in my worstcase we could end up with a (limited?) number of official preflashed Xperias sold by jolla, and an image you can flash to self owned xperias but with all license problems of regular community ports.

Pay for the port? How do you mean to set that up? Poeple would take it as downpayment for tablet refund or just share it for any reason. Not a good move. People might want to try it first, not use it. Hope jolla is smarter and don't try a stunt like that. Luckily I'm pretty sure it won't happen.

I wouldn't mind to pay for it if it means official support and regular updates.

Again that's the issue.

There could always be both the open version without AD and the licensed version.

Sounds good. Maybe even three or more. One for poeple that don't want to pay, one for poeple that wants to pay, one for poeple that wants refund. One for poeple that wants updates, and then one for ordinary people.

I wish it was like purchasing a software for pc online.. Pay for it and download the official software.. Isn't that possible?

There is a port for oneplus x, but there is no alien dalvik. So I'll wait for Sony phones with Sailfish OS version, and if there's an alien dalvik I'll buy it.