If you want to use Stand in GTA Online, all you need is a license key.
If you haven't already, download the Launchpad and inject Stand.
Once you've got your license key via Sellix (who'll send you an email) or Discord, you just need to copy it and click Paste License Key in-game.
Your license key will be stored in
%appdata%\Stand\License Key.txt and automatically validated the next time you inject Stand.
You may share your license key and there are no "Hardware ID" restrictions. The only restriction applied to license keys is that you can only use it on one instance at the same time.