In general it's probably not a good idea, but it probably depends on the product. I have a web app that I charge a one-time fee for, but it only lasts for one

In general it's probably not a good idea, but it probably depends on the product. I have a web app that I charge a one-time fee for, but it only lasts for one year, so it's essentially a one-year non-renewing fee. It works because it fits naturally with how people use the product (it's for fantasy football so it lasts for one NFL season). Most web apps, like project management software, fit nicely into recurring monthly/yearly payments. Unless yours is very different from that then it's probably better to do recurring. You'll have recurring expenses to pay to keep the site running, so you'll need recurring revenue to cover those.