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For clients with accounts (did not use 'Guest Checkout'), you can now deactivate products from your account page using the '?' https://store.stardock.com/myaccount/products link:
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Guest Checkout Clients
If you do not have an account (used guest checkout), you can still create an account here to use this feature: https://store.stardock.com/createaccount
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From the machine you wish to deactivate, open the configuration for the application and then go to the help/about section and then click the following (Fences Start11 is shown in the following example):
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