Even if you get a few months of reliable support, you still have to switch which will cost you dearly.
Often what is done is source escrow. The source is given to a third party, and if anything goes wrong the third party releases the source to the one who purchased the product.
Even this sounds like a bad outcome for users of the tool. One minute you're building a product, the next you're stuck maintaining a closed source database.
Often what is done is source escrow. The source is given to a third party, and if anything goes wrong the third party releases the source to the one who purchased the product.