"People won't know the value of my service if they can't use it!" means that you either aren't doing a good enough job showing them the value of your service up front, or you have an incorrect pricing model.
Let's take Stripe as an example. It is absolutely free for you to create an account, browse the dashboard, read their API documentation, etc etc etc, but they take their cut of every single financial transaction you do on their platform. There's no trial - either you find value in Stripe's services, or you don't.
Notion has a free tier for single user seats because that's their marketing plan. The moment you want to use Notion for what it's built for, team use, you're paying per user - again, there's no trial period there. Same for companies like Atlassian or IFTTT or Zapier or on and on and on.
"You get our full service for X days for free, then you have to start paying" is incorrect for _all_ values of X. Either, "you have to pay to be a user of myproduct.com" or "you can be a free user of myproduct.com but once you get to a level where you're serious about using the product, you have to pay" is the correct strategy.