At the end of a Season, your Season Tokens will be converted to Tokens, up to a maximum of 2,000 Tokens per Season.
The regular conversion rate for Season Tokens is 3%, meaning you'll be able to convert a maximum of 66,666 Season Tokens to receive 2,000 Tokens.
Purchasing the Legend Pass will double the conversion rate to 6%, meaning you'll only need 33,333 Season Tokens to receive the maximum number of 2,000 Tokens at the end of the Season.