If you log-in to your Lickd account and visit your My Account > Licenses section, you will find the attribution text for each music license you've purchased.
Your My Account area can be found here, or by clicking your account picture in the top right-hand corner, or the burger menu (3 lines in the top right-hand corner) and then your account name.
From the My Account > Licenses section, click the 'View video attribution' button and you'll be shown the unique attribution text which you will need to copy and paste into the video description.
However, it's important to note that this will not necessarily protect you from a claim.
If you are licensing a track from Universal Music Group (UMG), this will require manual intervention for clearing your claim. Please click here for more information.