By purchasing SongKong you get:

At any time after a year you can continue to use your existing version of SongKong at no cost or for a small fee purchase another year of free version upgrades, the year period starts from the day you purchase the version upgrades package.

Pro and Commercial offer additional features over the Standard version, full details here

License Type Price Purchase
SongKong Standard £25 ($31 USD)
SongKong Pro £35 ($43 USD)
SongKong Commercial £99 ($122 USD)
Upgrade Standard to SongKong Pro £12 ($15 USD)
One year of version upgrades £10 ($13 USD)

Please Read
The total price for SongKong is shown above, there are no other additional taxes.

If purchasing a Pro Upgrade using Paypal the license will be sent to your registered Paypal email address, please ensure this is the same address as your license is registered to otherwise the new license will not work.