If you have purchased "f secure safe" and want to take down the program again, it´s not possible. You have to change your routine.
This is more as feedback OR does help needed?
Maybe your situation/meanings can be about difference view (and some potential explanations); And situation can be based on certain platform. Since not clear about "why not possible to download F-Secure SAFE" (or with which step); But some of potential unofficial suggestions under spoiler:
Do you mean:
-- you already with F-Secure SAFE subscription and then did purchase for "F-Secure SAFE" as renew (or as another purchase with reduce price or so)?
-- OR you purchased F-Secure SAFE as first try and after register/login your account - it says that not possible to download "installer"?
-- OR you downloaded installer from My F-Secure Account and run it under device with current 'expired'-installation - but installer just trigger window with "F-Secure SAFE is already installed" (?); Or when downloaded application from store;
(valid for Windows - but most of meanings common for all platforms):
Common design -> if you already with "registered" account for SAFE ("your mail-address in use" -> not possible to use it with another My F-Secure Account); But maybe such situation possible to sort with F-Secure Support Channels; Or by creating fresh "My F-Secure Account" with another mail (or if your "mail-provider" able to support kind of aliases);
Registration under portal should ask for 'subscription-code' (or with certain instructions take automatically); And under My F-Secure Account should be ability to enter/add subscription code (as renew or re-validate it); If not possible with certain situation - maybe F-Secure Support Channels able to sort it too;
When you logged under My F-Secure Account portal and then download installer (it bundled with 'subscription-activation'-key) -> when you launch it --- usually it refresh your subscription under device (if there is already installed SAFE); And if there is expired state -> it will trigger valid state;
Also maybe certain situation covered by Knowledgebase:
Sorry for my reply.