Licensing

Profiles are associated with a user license. Licenses are how Salesforce charges for the
Force.com platform when you’re ready to go into production with an application. Salesforce
has many license types to provide flexibility in pricing, but the most basic licenses
are Salesforce and Salesforce Platform.The Salesforce Platform license allows full use of
Force.com but disables the business domain-specific functionality such as CRM or SFA.
For example, a Salesforce license grants you the use of the Opportunity and Case objects,
but a Salesforce Platform license does not. Sometimes even infrastructure features are
downgraded. For example, profiles for a full Salesforce license can delegate administration
on standard and custom objects.The Salesforce Platform license limits this feature to custom
objects only.
Planning ahead pays in regard to licensing Force.com. If you are sure you do not need
the extra features of the Salesforce license, select the Salesforce Platform license for your
profiles.This cuts down on the number of objects and features you see during development
and prevents you from accidentally referencing one of them.Also, in order to assign
a user to a profile, that user must have a user license that matches the profile.Your custom
profile cannot be associated with a different license after it has been created.