Hi,
I doubt 'subscriber management' is related to the LACP link flaps.
I would rather look at LACP and why LACP is timing out [LACPD_TIMEOUT messages].
The following commands may provide more info:
show lacp interfaces aex show lacp statistics interfaces aex show lacp timeouts aex
You could run the commands against the physical LACP member interfaces as well.
Cheers,
Ashvin