ALWAYS have a lifetime free plan. It's okay to make it a useless lifetime free plan (your data disappears every 2 weeks; you have a 3 email per day quota; etc.). It just need to be enough to seriously evaluate your product, and if it has APIs, to develop to them. There are sometimes good reasons to do more, and sometimes not. But that's the minimum.
In the early days of AWS, I would build thing on AWS' free tier, and they turned into products later. One product is making AWS millions (literally). AWS lost out when I changed orgs, my one-year free tier quota was gone, and I couldn't do the same at future orgs.
At big organizations, the overhead of a PO is sufficient that you don't do it unless you have a compelling business case. Free plan allows you to build a business case over a weekend.
I've gone free->paid many times.
It's worth noting the figures here. The case for a free plan is much more compelling for a Fortune 500 company who will sign a million-dollar contract than for a small business.