diff --git a/src/dds_endpoint.vhd b/src/dds_endpoint.vhd
index 11e1edc..9500f5e 100644
--- a/src/dds_endpoint.vhd
+++ b/src/dds_endpoint.vhd
@@ -277,6 +277,8 @@ architecture arch of history_cache is
     signal dynamic_next_instance, dynamic_next_instance_next : std_logic := '0';
     signal inst_data_variant : INSTANCE_DATA_VARIANT_TYPE := VAR_1;
     signal abort_khg : std_logic := '0';
+    signal lifespan_time, lifespan_time_next : TIME_TYPE := TIME_ZERO;
+    signal is_lifespan_check, is_lifespan_check_next : std_logic := '0';
     
     signal status_sig, status_sig_next : std_logic_vector(STATUS_KIND_WIDTH-1 downto 0) := (others => '0');
     signal sample_rej_cnt, sample_rej_cnt_next : unsigned(SAMPLE_REJECTED_STATUS_COUNT_WIDTH-1 downto 0) := (others => '0');
@@ -463,6 +465,8 @@ begin
         deadline_miss_cnt_next          <= deadline_miss_cnt;
         deadline_miss_cnt_change_next   <= deadline_miss_cnt_change;
         deadline_miss_last_inst_next    <= deadline_miss_last_inst;
+        lifespan_time_next              <= lifespan_time;
+        is_lifespan_check_next          <= is_lifespan_check;
         ack_dds                         <= '0';
         inst_data_variant               <= VAR_1;
         done_dds                        <= '0';
@@ -483,12 +487,24 @@ begin
                 
                 
                 -- DEADLINE QoS
-                if (DEADLINE_QOS /= DURATION_INFINITE and deadline_time < time) then
+                if (DEADLINE_QOS /= DURATION_INFINITE and deadline_time <= time) then
                     -- Reset Timeout
                     deadline_time_next  <= deadline_time + DEADLINE_QOS;
                     
                     stage_next          <= CHECK_DEADLINE;
                     cnt_next            <= 0;
+                -- LIFESPAN QoS
+                elsif (lifespan_time <= time) then
+                    -- Reset Timeout
+                    lifespan_time_next  <= time + TODO;
+                    
+                    -- Samples Available
+                    if (oldest_sample /= SAMPLE_MEMORY_MAX_ADDRESS) then
+                        cur_sample          <= oldest_sample;
+                        sample_addr_next    <= oldest_sample + SMF_NEXT_ADDR_OFFSET;
+                        stage_next          <= CHECK_LIFESPAN;
+                        cnt_next            <= 0;
+                    end if;
                 elsif (start_rtps = '1') then
                     case (opcode_rtps) is
                         when ADD_CHANGE =>
@@ -1575,6 +1591,18 @@ begin
                         -- Continue Processing
                         stage_next  <= GET_NEXT_SAMPLE;
                         cnt_next    <= 0;
+                    elsif (is_lifespan_check = '1') then
+                        -- Reached End of Samples
+                        if (next_sample = SAMPLE_MEMORY_MAX_ADDRESS) then
+                            -- DONE
+                            stage_next  <= IDLE;
+                        else
+                            -- Continue Search
+                            cur_sample_next     <= next_sample;
+                            sample_addr_next    <= next_sample + SMF_NEXT_ADDR_OFFSET;
+                            stage_next          <= CHECK_LIFESPAN;
+                            cnt_next            <= 0;
+                        end if;
                     else
                         -- DONE
                         stage_next  <= IDLE;
@@ -2520,6 +2548,51 @@ begin
                             null;
                     end case;
                 end if;
+            when CHECK_LIFESPAN =>
+                -- Precondition: cur_sample set, sample_addr (Next Pointer of cur_sample)
+                
+                case (cnt) is
+                    -- Preload
+                    when 0 =>
+                        sample_addr_next    <= cur_sample + SMF_LIFESPAN_DEADLINE_OFFSET;
+                        sample_ren          <= '1';
+                    -- Next Pointer
+                    when 1 =>
+                        sample_addr_next    <= sample_addr + 1; -- Lifespan 2/2
+                        sample_ren          <= '1';
+                        
+                        -- Latch Next Sample
+                        next_sample_next    <= sample_read_data;
+                    -- Lifespan 1/2
+                    when 2 =>
+                        sample_ren  <= '1';
+                        
+                        long_latch_next <= sample_read_data;
+                    -- Lifespan 2/2
+                    when 3 =>
+                        tmp_dw  := (0 => unsigned(long_latch), 1 => unsigned(sample_read_data));
+                        
+                        -- Sample Lifespan Expired
+                        if (tmp_dw /= TIME_INVALID and time >= tmp_dw) then
+                            -- Remove Sample
+                            sample_addr_next    <= cur_sample + SMF_PREV_ADDR_OFFSET;
+                            stage_next          <= REMOVE_SAMPLE;
+                            cnt_next            <= 0;
+                        else
+                            -- Reached End of Samples
+                            if (next_sample = SAMPLE_MEMORY_MAX_ADDRESS) then
+                                -- DONE
+                                stage_next  <= IDLE;
+                            else
+                                -- Continue Search
+                                cur_sample_next     <= next_sample;
+                                sample_addr_next    <= next_sample + SMF_NEXT_ADDR_OFFSET;
+                                cnt_next            <= 0;
+                            end if;
+                        end if;
+                    when others => 
+                        null;
+                end case;
             when GET_SAMPLE_REJECTED_STATUS =>
                 if (ready_out_dds = '1') then
                     cnt_next        <= cnt + 1;