If you have purchased multiple desktop seats then you will be given a licence key to share out across your users.
To do so then you should:
Step 1: Register an account with gallery.alteryx.com (you will already have an account if you have previously registered a trial, so just log in)
Step 2: Click on your profile image and select Settings
Step 3: Click on the Designer Licences tab
Step 4: Now type in an email address to share the licence, if they haven't previously registered you will need to invite them to share the licence
Step 5: The user will now receive an email from noreply@Alteryx.com something like the below:
They can now follow the instructions here.