I have an app on the App Exchange that is free. I'd like to develop some additional features that will cost money. Do I need to create two separate apps, or is it possible to create just one app?
I'm thinking there would need to be a way to restrict certain pages, features, and sObjects depending if the user has the appropriate license.
You'd want two packages, a base package and an extension. There's no way to license "part" of a package. The base package could detect the presence of the extension package, and call a method via an interface.
global class IPremiumVerifier {
Boolean isLicensed();
}
public class CheckPremium {
public static Boolean isLicensed() {
try {
return ((IPremiumVerifier)Type.forName('prempack','PremiumVerifier').newInstance()).isLicensed();
} catch(Exception e) {
return false;
}
}
}
global class PremiumVerifier implements basepack.IPremiumVerifier {
global Boolean isLicensed() {
return UserInfo.isCurrentUserLicensed();
}
}
If the features you want to restrict have Apex code e.g. Visualforce pages or @RestResource API's or SObject creates or updates or deletes (for which you have added triggers to enforce licensing), then you can use the UserInfo.isCurrentUserLicensed(namespace) to allow access for license users and block access for unlicensed users.
I caution against separating into two (or more) packages so you can use Salesforce's License Management App (LMA) unless you are sure you need to. It complicates the development process and because global classes and methods can't be changed once packaged makes it difficult to evolve your code.
Another alternative is to roll your own feature license mechanism within the one package. One approach is to issue encrypted feature keys that incorporate the org id so are tied to a particular customer's org. Another is to add checkbox custom fields to the License object in the LMA and for your app to call out to a site in your LMA org to check those flags.
