Hi Joshua,
This is Wil, one of the independent advisor, an expert with Windows 10 and a fellow Windows 10 user like you.
When it comes to purchasing licenses, it is always safe to purchase it directly from Microsoft to make sure that you will be getting a genuine retail license of Windows 10. Sure that there are a lot of stores that sell Windows 10 product keys for cheap but most of them provide evaluation keys or volume licenses that are only meant for organization or company use only. As for OEM keys, OEM keys are used by computer manufacturers to activate Windows 10 on the computer that they sell. It can only be used on the original computer it came with. And for licenses on a different region or country, you won't be able to use licenses for another country in Australia as all licenses have geo-restrictions on them.
https://answers.microsoft.com/en-us/windows/for...
https://answers.microsoft.com/en-us/windows/for...
I hope the information I provided will help you. If you need further assistance please do reply back and I will respond as quickly as possible. Have a nice day.
Thanks,
Wilfred P.
Independent Advisor