Activiti on itself is Apache licence, hence you can use it however you want. Activiti is supported as workflow engine in Alfresco. So when you'd buy an Alfresco licence, you also get Activiti support (but limited to the Alfresco integration).
However, since you state you also want migration, I think the best it to go with one of the companies that have knowledge around Activiti and offer support for it. Camunda http://www.camunda.com/ fits that requirement and is very activie both on the code as on this forum, but there are probably others too.
Hello Joram, we are also starting on a new BPM based project and considering Activiti as a viable option. Your above response is helpful about the licensing. But who should we be contacting for technical support related to Activiti 5 in the future, is it you guys at Activiti? or only Alfresco as you suggested.
