You could provide an "Export Data" function, and even supply them with regular, scheduled exports.
Also - you can still license your product with a closed source license, but allow your customers to run "On-Premise" ... i.e. they can still run your product for themselves, and own their data, but are also paying you a license fee for the pleasure.
It's a different revenue model, but can work - afterall, this is how business was done with software, pre SAAS.
Often, companies who license in this way offer $xxx.xx per year - getting them support and upgrades for the year. Then, if they cancel after the year is up, they get to keep it - with no upgrades. It's important that your pricing model reflects this scenario.
One of the upsides of this model is that you have zero infrastructure costs.
Also - you can still license your product with a closed source license, but allow your customers to run "On-Premise" ... i.e. they can still run your product for themselves, and own their data, but are also paying you a license fee for the pleasure.
It's a different revenue model, but can work - afterall, this is how business was done with software, pre SAAS.
Often, companies who license in this way offer $xxx.xx per year - getting them support and upgrades for the year. Then, if they cancel after the year is up, they get to keep it - with no upgrades. It's important that your pricing model reflects this scenario.
One of the upsides of this model is that you have zero infrastructure costs.