Many may believe that Samsung stopped paying royalties to Microsoft for Android apps because of the viability of Microsoft's Android apps, but that's not true. Samsung's position is that Microsoft's acquisition of Nokia broke the agreement between them.
This was of course expected in legal circles following the case, who say that Samsung is simply adding another argument to their position that the agreement between them is invalid on a business level. The agreement was made in 2011, wanting Samsung to manufacture phones with Windows software, which did not happen since the market for such phones is quite small and shrinking. Therefore, Microsoft did not lower the price of the rights, since under the agreement a certain number of devices had to be manufactured.
Furthermore, as Samsung claims, Microsoft's purchase of Nokia makes the latter a purely competitive company and is unable to share sensitive information with it for future projects.
Samsung paid Microsoft over $1 billion in 2013 for royalties on sales of up to 300 million phones. So they're justified in wanting to end the deal
