After modifying your type library, you'll want to save and register the type library information. 

Saving the type library automatically updates:

• The binary type library file (.tlb extension).
• The Project_TLB unit that represents its contents
• The implementation code for any CoClasses that were generated by a wizard.

The Type Library Editor gives you options for storing your type library information. Which way you choose depends on what stage you are at in implementing the type library:

• Save, to save both the .TLB and the Project_TLB unit to disk. (It is accessible through FileSave in the IDE.)
• Refresh, to update the type library units in memory only.
• Register, to add an entry for the type library in your system's Windows registry. This is done automatically when the server with which the .TLB is associated is itself registered.
• Export, to save a .IDL file that contains the type and interface definitions in IDL syntax.

All the above methods perform syntax checking. When you refresh, register, or save the type library, Delphi automatically updates the implementation unit of any CoClasses that were created using a wizard. Optionally, you can review these updates before they are committed, if you have the Type Library Editor option, Apply Updates on.