In the 2012 I bought a JomSocial Professional license not renewed (License Number: 100004825): until now I created a large community of about 8000 people, based on JomSocial 2.6.1 running on Joomla 1.5.26.

Now I need to upgrade the existing community to the latest JomSocial on Joomla or Wordpress. My question is how to achieve this upgrade. Keep all users and all published content (posts, comments, discussion, groups, etc.) is a requirement.

I'm working for an University: pay support and renew the license is not a problem.

HI, Francesco.

Thank you for contacting us.
Oh.. Joomla 1.5? JomSocial 2.6.1... oh, you're still in Middle Ages now :)
First of all you'll need to purchase a good migrator to migrate Joomla!.
Then you'll need to do a tier upgrade for JomSocial.
Please, read this:

documentation.jomsocial.com/wiki/Joomla_...n_With_JomSocial_2.6
documentation.jomsocial.com/wiki/Updatin...d_JomSocial_Versions