I currently have 7 licenses, and I need 8 of them. I haven't found an option to buy just one more. Do I really have to buy package of ten to get to my goal? That way I'd be wasting money on 2 licenses I wouldn't even use.
Sorry for my reply. I'm also only F-Secure user (their home solutions);
I able to think that possible to try contact direct F-Secure Support channels (chat/phone) and ask about such ability:
But as my own unofficial suggestion/feelings (under spoiler some meanings -> but as I noted after spoiler: not really useful words.. mainly):
If you do not mean that this article is valid (but option for "one else PC" is not available)..... probably I able to think only about potential workarounds like purchase another subscription/license for one device only; With my own experience if we choose "buy" under next webpage:
https://www.f-secure.com/en/web/home_global/internet-security (called as "Internet Security", but online store call it as "F-Secure SAFE for all platforms"): we able to choose "ONE" device subscription (€49.90) compare to F-Secure SAFE "1-3 devices" (€59.90);
Only as potential workaround for situation if F-Secure Support do not create/explain any proper steps to do things... which you want.
I able to think that previously (at least) there was option to "add one else PC" for renew state;
// later edited: ^ my unofficial suggestion not really useful; because I re-read your tries.. and looks like that package for "ten" with less price than "your current seven-package + package with one device" (except potential 'one more device' for current subscription as bonus or something like that); So.. probably required to ask F-Secure Support for certified answer. Maybe this is technically possible (based on this article - but where explained 'upgrade' from five devices to seven devices; which indeed possible to do);
Or as noted with another reply -> situation can be based on certain setting;