commercial-application

This question maybe a better fit on The Business of Software forum but despite my post on there , I'm still unable to determine the following: Can I use the Google API to build commercial software? If not how can the people behind Byline charge for their app? Update: I'm specifically interested in Google's Picasa & Reader APIs From the Google Terms of Service : 5.3 You agree not to access (or attempt to access) any of the Services by any means other than through the interface that is provided by Google, unless you have been specifically allowed to do so in a separate agreement with Google .

How do you protect your commercial application from being installed on multiple computers from people who only own one license? Do you think it's a good idea to have more than just a serial based scheme? My general rules are Huge deployments in commercial environments - Audit Medium deployments of low value software < $1000 / seat - License key activation Small deployments of high value software > $10,000 / seat - Dongles The following method works well, as long as you have a public server at your disposal: Serial based protection, user must enter a serial before using the program On first