Hello,
this is an excerpt from the full document linked below:
Flexible NetFlow is supported only on the Catalyst 3750-X and 3560-X switch running the IP base or IP services feature set and equipped with the network services module. It is not supported on switches running the NPE or the LAN base image.
Catalyst 3750-X and 3560-X Software Configuration Guide, Release 15.0(1)SE
http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750x_3560x/software/release/15-0_1_se/configuration/guide/3750xcg/swmnetflow.html#pgfId-1335576
Sorry, wrong answer. You were asking about the 3650, not the 3560.
Cisco IOS XE 3.3SE IP Base is the minimum requirement.
http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3650/software/release/3se/flexible_netflow/configuration_guide/b_fnf_3se_3650_cg/b_fnf_3se_3650_cg_chapter_010.html#reference_86EE0195581F4A79BA75E6A335A46634
