Sandboxie 5.22 Lifetime Home License Fails Activation

I have to use version 5.22 because I am on Windowx XP and AFAIK it is the last one compatible with this OS.

Yesterday the renewal request message ( "Sandboxie is registered but the license must be reactivated" ) appeared on the screen, but pressing the activation button I get the following error message:
"Product activation failed:
The connection with the server was reset [ err 12031 by 14 ]
If you need to activate Sandboxie on a computer that does not have internet access, please see the Sandboxie licensing FAQ for information about Offline Activation."

Then I tried the offline activation procedure ( www.sandboxie.com/.../activate-offline.php ), but after entering all the requested data and pressing the "Get Ectivation Key" button, a "502 ERROR. The request could not be satisfied." error message appears.

In 2016 I purchased a Lifetime Home License for 3 computers paying € 57.65, and everything worked correctly so far.

Now it seems no longer possible to reactivate the license, and because of this the program only works as in the old free versions that had the extended features not working ( "SBIE1310 Extended features are disabled until the license is reactivated." ).

How can I completely restore the features of the program I paid for?

Please can you provide me with a solution to have the program completely working again?

Looking forward to your feedback, best regards.
Maurizio