I'll answer this question assuming it has one implication: was an average Soviet person aware, that the equipment had come to the USSR as virtually free aid, as people in the West think of it (and which it may well be)?
Certainly operators, maintenance technicians of aircraft, trucks, tanks, engines knew it came from the US or Britain. I consider it to be redundant to provide links here, since they definitely saw gauges with English inscriptions etc. and the USSR was not a 100% 1984 to "fix" such things. And they talked to other people, so, as was mentioned in other answers, it was not a secret.
But did people think of it in the same terms as it's usually understood in the West, as free aid to the USSR? I doubt that. I suspect that many don't think this way today either. Even I, who is generally interested in the topic of WW2 was sure, that everything was purchased by the USSR.
To understand how this happened to be, I'd suggest that one looked into a way Lend-Lease is covered in government approved textbooks today.
This is an excerpt from a Ukrainian high school history textbook of 2018 (Ladychenko, ISBN 978-966-11-0311-4, pages 139-140):
A British military-economic mission arrived as soon as June 27 . The treaty on mutual action in the war against Germany was signed in Moscow on July 12 1941 on the proposal of the Soviet government.
In his turn, F.D. Roosevelt, beginning from July 21, allowed to start selling arms and military materiel destined to the USSR. Some in Washington hoped to make money on this, receiving from the USSR "all … [sic] the gold, which would come as payment for the supplies of the goods, until it's exhausted", — was recollected by Secretary of the Interior Harold L. Ickes.
But nevertheless those steps started the formation of the Anti-Hitler coalition — the alliance of countries with such opposing interests, that it could have never been possible under different circumstances.
Peculiarities of military aid to the USSR's allies [sic]
The supplies of arms, military materiel and strategic commodities was provided according to the Lend-Lease Act, passed by US Congress in March 1941. It allowed the US government to provide goods and services in loans, leases and credits.
All the deliveries by the Allies didn't exceed 3% of food and 4% of industrial production of the USSR, used by it during the war.
There could have been more mutual gain, had the USSR received from the Allies radar technology secrets, vitally necessary to fight German aircraft. That technology belonged to both the USA and Britain. But initially the American government vetoed its transfer, then when in Washington switched their mind, the British opposed it.
I looked into a Russian textbook of 2007 (ISBN 978-5-94853-678-1) and this is from there (pages 154-155):
Despite strong isolationists feelings US Senate passed the Lend-Lease law. According to it the USA provided aid to countries, whose opposition to aggression was recognized as vital to the defense of the US. Lend-lease deliveries were due to be payed after the war, only in case, if they were not used for military purposes. This way, even though the USA were reluctant to go to war, they played the role of a non-fighting ally of Britain.
And I can say, that 20 years ago the Ukrainian text was virtually the same.
So as one can see there are appalling differences between the English Wikipedia article about Lend-Lease, and the narrative which the majority of people in the former USSR are familiar with.
When I read the Wikipedia article today, I was stunned. What I used to know about Lend-Lease was that it started in 1940 or 1941 as a "cash and carry" program, then that some British ships were sunk carrying gold from the USSR (from here you assume that it was a usuall practice for them to return with gold, because not all of them were sunk) and that the American embassy in Russia 10-15 years ago claimed, that the USSR hadn't payed everything and formally was still owing several millions of dollars, though the embassy didn't press for payment.
So I have serious reasons to believe that during ww2 people in the USSR thought that the American/Brithis goods were purchased by the Soviet government, I simply cannot imagine that during Stalin's reign it could be different, if that is how it's been being portrayed for the last decades.