improvement of the economy and the Kronstadt rising
One of Lenin’s motives for the NEP in 1921 was to improve the economy after the the Tsar- WW1 had negatively affected production and the economy. 13 million peasants had been conscripted to fight and 9 million had died, resulting in a drastic shortage of farmers and therefore grain.
As well as this, there had been a serious inflation problem. The gold standard (where the economic unit is based on a fixed quantity of gold) and so many more notes were produced. This greatly reduced the value of money, and soon prices had quadrupled in some sectors.
As well as improving the economy, the NEP was also implemented as a reaction to the Kronstadt rising. This was a 1921 uprising where the Kronstadt sailors- the Bolsheviks’ fiercest supporters as well as being sailors part of one of the main groups the Soviets (soldiers, workers and sailors) represented- mutinied against them as a protest against War Communism.
The Bolsheviks saw this as a warning, since their less fierce supporters could just as easily rise against them, but they had won the Civil War so the Whites were not dangerous. This meant that Lenin could act in ways other than repression without facing dangerous hostility, and he was able to implement the NEP, a temporary economic plan.