A red cross for a particle plug-in in Adobe After Effects (AE) usually means that this is a trial or unauthorized version of the plug-in. The method of removing the red cross usually involves the following steps:
Purchase or activate the plugin: If you are using the trial version of the plugin, you can remove the red cross by purchasing the official version and entering your license key. Usually, this information can be entered in the plugin's settings or on the About page.
Update or reinstall the plugin: Sometimes, software updates can cause issues with license validation. Trying to update the plugin to the latest version, or uninstalling it and reinstalling it may resolve the issue.
Check compatibility: Make sure your AE version is compatible with the plugin version. Some plugins may not support newer or older AE versions.
Contact customer support: If none of the above steps resolve the issue, contacting the plugin's customer service or technical support team may be the best option. They can provide more specific solutions or help you with your licensing issues.
Check your network connection: Some plugins may require a network connection to verify the license. Make sure your computer is connected to the internet and check if your firewall or security software is blocking network access for AEs or plug-ins.
Keep in mind that using unauthorized software or plug-ins not only violates copyright laws, but can also pose a security risk. It is always advisable to use genuine software and plugins.