If you need grant temporary access to your publication without creating a username and password and subscribing them, you can provide them a link which contains a token. The token will last for around 7 days.
To find the free access link, go to your account on the partica dashboard and click on the cog icon on the right side of the interface for the publication that is secure, that you want to grant access to.
Doing so will show the option to access url settings. Click on Url settings.
You will then see a page with a number of tabs on it. Click on site authentication, you will then see the automatic login link with a click here text button. You can copy the click by right-clicking on here and copy the link location.
This link will grant temporary access. DO NOT CHANGE ANY SETTINGS.