I recommend reading this excellent case study of how Evernote got its customers to pay for its service which was initally free. To quote the article
But according to one hugely successful startup which operates under
the Freemium model, Evernote, converting free to paid is all about
engagement.
"The easiest way to get a million people to pay for non-scarcity
product may be to make 100 million people fall in love with it,” Phil
Libin, the CEO of Evernote told the Founder Conference. His users,
says Libin, are his marketing team.
The key to getting that number higher is to keep users (aka fans)
happy. “It’s more important that you stay than you pay,” Libin said.
“Once Evernote gets under your skin, you never want to stop using it.”
Also user research has shown that when users are aware of what a product is capable of doing and when the available features add value to the product they are more likely to be willing to pay for it as soon as they get used to it and find out that they cant exist with out it. To quote another study about a social media sharing app called Buffer
Lesson 1: User Flows Should Focus on Retention, Not Revenue
A key user experience (UX) lesson that we discovered early on was that
we needed to concentrate on keeping our customers rather than
generating revenue.
This is how we learned this lesson. Our initial landing page’s user
flow was as follows:
- When you first see our landing page and click on the sign-up button, we would show you a "subscription plans and pricing" page.
- From there, you would be required to choose either the "Free" plan or one of our paid plans.
- After you’ve picked the right plan for you, you would be able to sign up by providing your details (e.g., your name, email address, and
so forth).
With this user flow, the rate of people choosing one of the paid plans
upon signing up is high, thus allowing us to generate revenue early
on.
However, we quickly learned that users who picked to pay for the
product before getting the chance to use it sent our churn rate
through the roof.
Why did this happen?
We found out that people would pay, but then they wouldn’t even start
to use Buffer, and eventually they’d cancel their subscription.
So we changed our sign-up user flow and philosophy of acquiring users.
We decided to say to ourselves, "Let’s get the person to start using
the product first so that they can experience first-hand the value of
our product, which will hopefully encourage them to upgrade to one of
the paid subscription plans."
That worked out a lot better for us.
As a result of this user flow redesign, two important things happened:
- More people signed up because we didn’t dilute the funnel with a pricing page as an interstitial.
- More people upgraded over time because they started to actually use the product, find value in it, and stick with us. Since then,
we’ve made many more product changes that give out more free features,
and our core product features are still free. Only after we’re sure
you’ve really seen lots of value from using Buffer that we would
encourage you to upgrade to a paid plan.
Making user flows that focus on user-retention was an important
discovery for us.
Hence my recommendation would be the following :
- Inform your users in advance that you will be migrating to a paid model soon and when so that they know when to expect it and are not surprised
- Inform them of what will be available in the free version but also emphasize on the benefits of the premium version.
- Consider the concept of a trial before you buy for new users so that they know what they are getting.(500px does this brilliantly where it signs you directly for the full fledged trial option and allows you to get used to the benefits).
I also recommend reading this UX Myth article : People are rational for additional inputs.