From what I understood you need something like this:

SELECT a.*

FROM sales_log_tbl a

LEFT

JOIN membership_record_tbl b ON a.member_id = b.member_id

AND a.company_id = b.company_id

AND a.purchase_dt >= b.membership_effective_dt

AND a.purchase_dt < b.membership_term_dt + 1 --Do you know why you should use this?

WHERE b.member_id IS NULL

I remember there are other ways you can do this but this is one way to accomplish.