• How long implementations take
  • How easily it is to migrate to a new version of the product
  • How much the customer has spend on customizations
  • How often new versions are released
  • How quickly the new released versions are available
  • How much you are still earning on the released product (Support and Maintenance contracts)

You have to state clearly if and when Support stops. At least a few years before you are planning to do so. This is an issue that has to be arranged in your Support and Maintenance contracts. Make sure Sales is properly informed about the end dates. Do not sell versions that soon will reach the end of their products lifetime to reduce thef risks to keep it mandatory in the air.