Random remarks:
* You have no moral obligation to release something as open source.
* Open sourcing a project is not free. It's work. You have to manage maintenance/releases/contributions/etc, in a way that will match your audience's expectation (much more than for a closed source app). If you fail to do so someone will fork it and de facto take over your project. In general, do not open source your project if you're not ready to put in the extra work.
* Typically when you open-source you don't sell licenses, you sell support contracts. If it's cheaper for enterprise customers to pay for maintenance than to update the software by themselves, they'll pay. If your software requires your expertise (i.e. it's complex and/or specialized enough) this might be a valid option.
* If you're still on the fence, consider releasing a 'lite/free' edition, i.e. closed source with some hard limits, so that individuals and small teams can use it at no cost, and then see where it goes regarding that particular edition.