Some extensions that are available for purchase offer the ability to try it out for a period of time. If an extension offers a trial, the trial period is displayed in the grey information box on the right side of the extension details page.
You’ll see an Install Trial button just below the Purchase button. This button only appears when you access the Extension Warehouse from inside of SketchUp – click Extensions > Extension Warehouse – and look at the extension’s details page. If you’re viewing the Extension Warehouse with an Internet browser, outside of SketchUp, the Install Trial button will be replaced with a link to this Knowledge Center article.
If the trial period expires and you decide not to purchase the extension, you should uninstall the extension. Otherwise, Sketchup will tell you each time you start that the extension trial has expired. You can uninstall an expired trial extension from the extension's details page or from your My Extensions page. You can only uninstall an extension when you access the Extension Warehouse from inside of SketchUp – click Extensions > Extension Warehouse.