Error: “It has not been possible to validate your software license. This may be because your license is invalid or has expired. Please contact your administrator.” when trying to register the Act! Link for Accounting.

Symptom:
When I try to register Act! Link for Accounting, I receive the Error: “It has not been possible to validate your software license. This may be because your license is invalid or has expired. Please contact your administrator.”

Product Details:
Product Family: Act!
Product: Act! Pro (UK edition), Act! Premium (UK edition)
Version: v18 and later

Environment:
Third Party: Sage 50 Accounts v21-v27

Cause:
This can occur if the serial number was entered incorrectly, if the Company Name was entered incorrectly, the Serial number is for a different version of Act! Link (V2 or V3), or if the Serial number has expired.

Solution:

1. Ensure that you have entered the serial number correctly and that there are no spaces before or after the serial number
2. Ensure that your Company Name has been entered exactly as it appears on your invoice
3. Verify version of Act! Link from Microsoft Control Panel
4. Look at the Expiry Date field and verify that the date has not already passed