Lead Ninjas works with a free LinkedIn account. You do not need a Sales Navigator or LinkedIn premium to be able to use Lead Ninjas. You can perform the 700 weekly actions with a free LinkedIn account as well.
However, you may need a Sales Navigator or premium subscription if you need the use the other features that LinkedIn offers with those subscriptions. For example:
Premium search filters: Sales Navigator has about 12 extra search filters. These additional filters help create targeted searches.
Save larger lists: With a premium or a sales navigator, you can save a list of up to 2500 contacts compared to 1000 contacts with a free LinkedIn account.
Ability to save more than one search per day in Lead Ninjas.