As soon as you install TallyDeveloper 2.7, you should launch the application and activate it. Not doing so, will lead to the product functioning on Educational Mode. Every time you launch the application, you will be prompted to activate the product at the TallyDeveloper License Activation Form screen. Press Esc to run in Educational Mode. By running the product in Educational Mode, you will not have TDL by and will not be able to compile a project file or decompile a TCP.
Follow the steps mentioned below to activate the product
1. Launch TallyDeveloper 2.7. To launch, you can either double click on the TallyDeveloper’s shortcut icon on the desktop or from the Start menu, select Programs > TallyDeveloper 2.7 > TallyDeveloper 2.7 . The TallyDeveloper License Activation Form appears as shown below.

2. Enter the valid Serial Number and Activation Key provided.
3. Enter your E- mail ID. This will enable us to correspond to you for future communications for product.
4. Click Submit .
If the Serial Number and Activation Key are found valid, you will get a response indicating the successful activation of the product.
Note: Tally.Developer 9 can be activated through an online procedure only i.e. the internet should be available on the same system.
Product activation validates that a particular product key has not been installed on more computers than is allowed by the End-User License Agreement (EULA). Activating the product is a simple process and it takes only a moment.