A question that gets asked at least once a week on the 1waylinks members forum is what happens to the links you have built if you quit 1waylinks. The answer is that as long as you keep your donor blog active and with all the blog posts intact then you will keep all your blog posts.
I think this clearly demonstrates that you should consider buying a separate domain so that you don’t lose all your links if you decide to remove the blog from your donor domain. Many people in the network are still using their money domains with the donor blog installed in folder or sub-domain of that money domain.
I don’t recommend doing that for two reasons: one is that the content being added to your donor blog could dilute the value of the content on your money domain and Google devalues your site and secondly if people start searching specifically for your money domain and discover lots of unrelated blog posts in the search engines then it could cause all kinds of confusion.
I personally use and recommend Namecheap to buy a cheap domain to donate to the network. Don’t forget though that the more domains you donate the more blog posts you can submit!