hi there,

[my question]
how can i create a "one-time-registration-code", meaning:
1) siteowner prepares e.g. 20 codes in BE.
2) siteowner hands out registrations-link with such a code to his client.
3) registration-page accepts code as a mandatory field.
4) used code is deleted/unusable from database.

[why?]
- my client wants to effectively shut down his registration page, except for when someone has such a code.

thanks in advanmce for any advice!
Bob