I bought Artio vm-invoice in August 2012 (I never updated - update link did not work), I forgot to renew my subscription and I had to buy another one (August 2013), the question is:
how can I install it?
I have to uninstall the previous one or can I install it on?
if I have to uninstall the previous version, how can I do?
if you have suggestions are welcome

virtuemart 2.08
joomla 2.5.6

Ivan