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Protection PLUS Compare Editions

You've developed your software, and now you need to address the issue of enforcing license compliance, but what tools do you need? The following information will help you determine which licensing client from the SoftwareKey System, either Instant Protection PLUS 3 or Protection PLUS 5 SDK, is the best choice for your needs.

For an additional perspective, you can also read our blog post: THE DECISION: Instant Protection PLUS 3 or Protection PLUS 5 SDK.

Instant Protection PLUS 3

Instant Protection PLUS 3 uses a wizard interface and requires little or no source code changes to implement the most commonly requested licensing business logic and user interface. It is a template that does most of the work for you, but still allows for a little flexibility and creativity.

If you are licensing a Windows desktop application, Instant Protection PLUS 3 is an excellent licensing client candidate with its quick and easy implementation. You can tap into thousands of lines of licensing code which are implemented for you by simply stepping through the Instant Protection PLUS 3 wizard and choosing your desired licensing settings.

Protection PLUS 5 SDK

Protection PLUS 5 SDK offers robust interfaces to give your development team complete control and flexibility over the licensing business logic and user interface that is presented to the user. With the Protection PLUS 5 SDK, your development team has a blank canvas and our APIs are their paint and paintbrush. There are separate editions available based on the programming language you are using and what platform(s) you need to support:

  • .NET Edition - Windows, macOS (Mono Framework), Linux (Mono Framework)
  • Native Edition - Windows, macOS, Linux, Linux (ARM)
  • LabVIEW Edition - Windows, macOS, Linux
  • Java Edition - Windows, macOS, Linux
  • Android Edition - Android

The overall process of using Protection PLUS 5 SDK is similar to Instant Protection PLUS 3, but you will use our API to implement the licensing into your application's source code. Protection PLUS 5 SDK has all the same licensing functionality that is available in Instant Protection PLUS 3, as well as additional features. You will have much more control and flexibility with the Protection PLUS 5 SDK, especially when implementing more complex licensing requirements.

Feature Comparison


Instant Protection PLUS 3

Protection PLUS 5 SDK

Supported Platforms


ARM / Raspberry Pi

Supported application types


desktop, web service

Source code changes required

in some cases1


License file format2

fixed field


License file encryption3


public key

Activation payload data size


no hard limit5

License file storage6

file system/registry


Proxy server support

authentication not supported7


UNICODE support

not supported


License dialogs

limited customization

fully customizable

  1. Instant Protection PLUS 3 source code changes - Depending on your application's language, environment, and license requirements, simple source code changes may be required. Simple license requirements for a Win32 PE application will not require any source code changes. Using the Instant Protection PLUS 3 DLL or using the Instant Protection PLUS 3 API to make calls into the licensing code in order to retrieve and update license information requires source code changes.
  2. License file format - Instant Protection PLUS 3 supports several pre-defined and user-defined data fields of various data types for purposes of licensing your application. The size of the file is fixed. Protection PLUS 5 SDK licensing libraries support several pre-defined and user-defined data fields with near limitless capability for storing licensing data.
  3. License file encryption / verification - Instant Protection PLUS 3 uses a legacy proprietary symmetric-based encryption technology. You choose a password to randomize the encryption. Protection PLUS 5 SDK licensing libraries use strong RSA digital signatures and public key cryptography. Because the key used to create the digital signature and to encrypt the data is kept private by SOLO Server or License Manager, it is very difficult to create a License File which will pass validation by these libraries. RSA key sizes are easily expanded / changed.
  4. Amount of custom license data passed during activation - Instant Protection PLUS 3 can only pass 14 bits of custom data during activation, which means that you will not be able to easily set multiple licensing restrictions in a single activation, such as an expiration date, which features to enable/disable, or a usage counter. Protection PLUS 5 SDK is able to pass a large amount of custom data during a single activation.
  5. Data limit recommendation - Although there is technically no limit to the amount of data you can send in the Protection PLUS 5 SDK XML license file during activation, we recommend keeping it limited to just licensing data that is under 1000 bytes. Using more data will start to degrade performance because all the data has to be decrypted.
  6. License file storage - Instant Protection PLUS 3 can store the license file in the file system or Windows registry only. Protection PLUS 5 SDK licensing libraries are designed in a manner in which the XML license file may be stored in any means convenient to the developer - file, registry, database, etc.
  7. Proxy server support - Some environments limit and monitor Internet connectivity using proxy servers, which can have an impact on your application's ability to activate through SOLO Server. Instant Protection PLUS 3 does not have support for proxy servers that require authentication. Protection PLUS 5 SDK can be configured to establish compatibility with most proxy servers.