I'd suggest adding:
"It is not possible to use more than one set of add-on userpic space. If you already have add-on userpic space and you purchase the add-on again, it will extend the time remaining on your current userpic add-on. You can not purchase multiple sets of add-on userpic space to upload more than 100 userpics.
If you have a Permanent Account, you can not purchase add-on userpic space, because you can always upload the maximum number of userpics allowed on LiveJournal."
to the end of the Userpic Add-Ons paragraph.