This is the FAQ about account subscriptions and upgrades.

Payment Methods

There are a variety of ways to purchase a subscription. The first and easiest way is to pay via PayPal using the Subscriptions page.

Alternative methods of payment are available for those who do not have access to a PayPal account:
MoneyPak Cards

Concerning the above methods, you must send a private message to an administrator with the information specified below:

•Name of Recipient (either yourself, or an account who you wish to gift to)
•Subscription Type and Length (required!)
•Transaction Amount (preferably in USD)
•Applicable Card Number(s)

Verify that your cards have money in them / are valid! You will be punished (and likely banned) if you send invalid codes / details of cards with no money in them.

Downloading your purchased programs

Once your account has been upgraded, you can download your program from their respective forums.
They are located in the osu! Paid Programs section of the forums (picture here).

If you are not upgraded, or you don't seem to be able to access these forums, contact an administrator. Provide proof of purchase, such as a screenshot of a transaction. Requests that fall under this category without any such proof will most likely be ignored.