There is no limit as to how many Summer Tokens can be exchanged for additional rewards.
Rules
Now you have the opportunity to buy some of the best vehicles Armored Warfare has to offer for Gold and earn bonus Summer Tokens in the process! These can be exchanged for additional rewards.
For purchasing vehicles and skins for Gold on this page, you will receive additional Summer Tokens: 10 per purchase, up to a maximum of 250 over the entire event period.
Complete daily missions and purchase items via this page in order to earn Summer Tokens. Summer Tokens can be exchanged for additional rewards using this page.
July 7, 15:00 CEST to July 18, 15:00 CEST
A Daily Mission is available: Win 3 matches in any mode. After completing this objective, you may pick up 3 Summer Tokens. Summer Tokens can be exchanged for additional rewards using this page.

There is no limit as to how many Summer Tokens can be exchanged for additional rewards.