Jack Li explains a difference between memory-optimized tables and memory-optimized table types:
This customer was puzzled because he delete existing rows. At any given time, there should not be more than 1 million rows. SQL Server should not have run out of memory.
This is actually by-design behavior documented in “Memory-Optimized Table Variables”). Here is what is state “Unlike memory-optimized tables, the memory consumed (including deleted rows) by table variables is freed when the table variable goes out of scope)”. With a loop like above, all deleted rows will be kept and consume memory until end of the loop.
Click through for the complete story.