Total avaliable memory fell below error level to 3%

Total avaliable memory fell below error level to 3%

Hi..
I just found a the logs below:
1. Total avaliable memory fell below error level to 3%
2. 100ms Timer has not cycled for 272953ms
3. LogSrv socket error--Client/Server socket - read failed (00002746 / An existing connection was forcibly closed by the remote host.)

and then my service engine closed. But i run again the service engine, no error pop up showing, but when i check the logs i found :

4. Error sending init1+ response failed. (MODBUS_ENERGY, 59637) [127.0.0.1:58218]
5. Driver connect error! Proxy connect failed (0x8001011F).
6. Licensing: Found license is not valid! (in my Process Gateway)

Question:
1. Total avaliable memory fell below error level to 3%, when it's happen i saw the Ram Usage is still fine, so what the mean of memory in the logs ?
2. And for point 2 & 3 it's related to Network and Security or it's from my zenon ?
3. for Point no. 6, I already check all my licensed is still valid, but in the logs is not valid. Is that really my license problem ?

Thanks