It all depends on the method you've used to purchase the software. If it's a digital application, then simply visit its official website, download the trial and use the registration data to activate the full version of the software. The same instructions you will find in the email used for this purchase.
For physical installations, simply insert the CD/DVD and follow the Autorun instructions.
There is no other process except the one provided above.
Note: For digital products, the applications and their registration data can be obtained from the member's area on the official website of the developers.