Hi,
I dont think there would be any license issues.
The steps to do this are
create a new FS
install new IFX version under the above FS
take a level 0 backup
bring down informix
copy existing onconfig, sqlhosts to the new INFORMIXDIR/etc
export new path, new INFORMIXDIR, ONCONFIG
start informix (oninit -v) when new envirnment variables are set for the session. Informix will do the internal migration of all databases.
Please do test the above before trying on Live.
I hope, I am not missing anything.
regards,
Nitin