when you enter and exit Thailand they register your movement in/out. I dont know if this register is something the Thai embassies can access, but given that immigration and embassies are both government bodies, I would assume that.
the visa is valid for a year where you can enter Thailand using the visa. But there is a maximum stay of 90 days per stamp.
If you time it right and make your last entry on the final days of the visa validity you can actually get almost 15 months of stay in Thailand on that same visa. (Initial entry and then Exit and reentry every 90 days - 4 times = 450 days)