1. Log into your account
2. Go to Settings & Members
3. Go to Billing, select Upgrade (I chose Personal Pro) and enter the code
4. You need to enter your card to checkout.
This will grant you $500 credit on your account.
Just tried it myself and got charged $0.00. Not sure how long this will last.
Notion is a collaborative workspace with notes, databases, kanban boards, wikis and calendars. I’m using it mostly for todo lists and project management.