Due to some issue with install/update on Joomla! 1.6 and 1.7. Here is a 2.6.4 version that fixed these issues.
Here are the changes:
@FIXED: Configuration cannot be saved
@FIXED: Not possible to save paidsystem plugin parameters
@NEW: Add Support for Joomla! 1.6 and 1.7 Extension Update Manager. (Note: Only notification of new version available, the installation is still manual, due to the fact that Joomla Software cannot check your subscription)
@FIXED: Issue with CSS for categories select (multiple categories). Remove "Style"
@FIXED: There was no "PaidSystem" menu type available during the creation of a menu item