advice Buying domain with free and open source software names

[globalcashsite]

Hi,

I found 3 free and open source softwares and domains are available in few extensions with name of these softwares. So is this fine to buy these domains?

And second question can I buy domain name with paid software name by adding some words like "download" or "update" or "news"?

Please give your suggestion.

Regards

GCS