Professionals can upgrade their free listings to sponsor listings at anytime and similarly downgrade their sponsor listings to free listings at anytime. Professionals can do that through the dashboard or by requesting an invoice outside the dashboard area.
Upgrades and downgrades are by listing. A user can have multiple sponsor listings and multiple free listings
Upgrade periods (monthly or yearly subscriptions) begin on the day of upgrade
When a user dowgrades a listing, their listing stays as Sponsor until the end of the period that was already paid