Lansweeper will only prompt you for a email address and language when you log into the helpdesk module (this includes the knowledgebase) for the first time.
My initial thought would be that you are using an AD account. However, in your AD, you do not have an email address entered in the email AD field. When Lansweeper rescans AD users it updates all the AD user fields and overwrites the email field back to being empty. Next time you enter the helpdesk, since you dont have an email linked to the account anymore, Lanswepeer will prompt you again.
The best solution is to either update your AD information or manually add an email address to your account by navigating to Configuration\User Access & Roles and make sure the "locked against scanning" is enabled as seen below