The one-event memberships (both one-day and multi-day) are commonly used for tryouts and as an "emergency" player at a tournament.  A member is limited to TWO one-event memberships per indoor season https://ed-hrvatski.com.  If the player wishes to join as a member for the rest of the season, then the member (or parent/guardian for junior members) should log back in to their member account and click to RENEW the membership.  The system will show a one-event UPGRADE option.  That is the choice the member should select.  That will upgrade the member for the entire season and it event gives credit for the one-event member fees already paid (once).