Yes, you can request a refund or exchange/upgrade of your commercial or academic server license up to 30 days after the original date of purchase. After the 30-day period, standard pricing for upgrades will apply and exchanges/refunds will not be available.
To request a refund/exchange within 30 days of payment, contact Atlassian’s Customer Advocate Team.
Please Note: Given the charitable nature of funds collected from Starter Licenses, Atlassian is unable to offer refunds or exchanges for Starter License purchases.
Source: Atlassian Purchasing & Licensing FAQ