GemBox.Document works in two different modes:

Free mode - free of charge, limited to 20 paragraphs.
Professional mode - requires purchasing a license key, no limitations.

Both modes use the same GemBox.Document DLL so there is no need to reinstalling the component when switching modes.

The first thing to do when coding with GemBox.Document is to instruct the component in which mode it will be used. This is accomplished by calling ComponentInfo..::..SetLicense(String) method with the specific license key parameter:

FREE-LIMITED-KEY, to use the component in a Free mode,
the license key that you receive after purchasing GemBox.Document, to use the component in a Professional mode.

Important
ComponentInfo.SetLicense method must be called before using any other class from GemBox.Document component.

Tip
ComponentInfo.SetLicense method can be called multiple times. It is only important that it is called with the same license key. Ideally, it should be called at the startup of your application. For example, it can be called in a Main method, an application startup event or a static constructor of your main class.

Tip

ComponentInfo.SetLicense method can be called multiple times. It is only important that it is called with the same license key.

Ideally, it should be called at the startup of your application. For example, it can be called in a Main method, an application startup event or a static constructor of your main class.

Evaluation

You can evaluate GemBox.Document free of charge and for an unlimited time period, just download the installer, install the component and use it in a Free mode.

Free mode delivers the same performance and set of features as a Professional mode, with the following limitation:

document content will be trimmed to first 20 paragraphs when loading or saving a document.

If you want to evaluate GemBox.Document performance beyond first 20 paragraphs, then handle ComponentInfo..::..FreeLimitReached event and set the FreeLimitEventArgs..::..ContinueAsTrial to true, like in this following code snippet.

CopyC#

// Set license key to use GemBox.Document in a Free mode.
ComponentInfo.SetLicense("FREE-LIMITED-KEY");

// Continue to use the component in a Trial mode when free limit is reached.
ComponentInfo.FreeLimitReached += (sender, e) => e.ContinueAsTrial = true;

// Here goes your application specific code.

CopyVB.NET

' Set license key to use GemBox.Document in a Free mode.
ComponentInfo.SetLicense("FREE-LIMITED-KEY")

' Continue to use the component in a Trial mode when free limit is reached.
AddHandler ComponentInfo.FreeLimitReached, Sub(sender, e) e.ContinueAsTrial = True

' Here goes your application specific code.

This option will enable you to read / write entire document content, with the following limitations imposed after the first 20 paragraphs:

When loading a document - on average, every 10th character in a document is replaced with a random character.
When saving a document - promotional header will be added to every document page.

Licensing

If you have evaluated the component and are satisfied with it, you can purchase the license key to use the component in a Professional mode - without any limitations.

After purchase, the only thing you need to do is to replace FREE-LIMITED-KEY with your purchased license key in ComponentInfo..::..SetLicense(String) method call.

Note
There is no another installer or DLL for the Professional mode. You should continue to use the reference to existing GemBox.Document DLL in your project when switching to Professional mode.

Professional mode also includes technical support with prompt bug fixes. For more information, see Technical Support.