What and who do you buy software from? - Thinking either content or tools, - and do you buy site licenses, subscriptions or just for specific year groups, and how do you administer or keep record of licensed software within your schools?

Just looking for a bit of feedback really following on from a conversation where the school stated that they only buy's MS Office and SIMS for the school, - the rest is down to department heads to spend against their budget. There appeared to be no centralised administration or knowledge of exactly what the teachers and pupils we using and wondered if that was the "norm".