i have asa 5505 with the asdm v5.2 (4), and the asa v7.2(4). This platform has a base license. if i upgrade adsm and asa on v6.2(1) and v8.2(2) if I lose my license and that you need to activate them? i configured site to site vpn (this firewall and the another) that i lose my configuration if i upgrade my firewall.
You dont lose license info if you upgrade the firewall, so no need to worry about it, you can easily upgarde the firewall, but just for safety we always take a back up of the ASA configuration and license.
Otherwise there are no issues with the license.