Are MQL4/5 IDE is free to Use or Developer Needs pay any royalties or Fees?

 
"MetaQuotes reserves the right to modify these MQL4 IDE terms and conditions at any time, on a general or individual basis, by publishing the revised MQL4 IDE terms on the MetaQuotes' Website or by otherwise notifying You of the revised MQL4 IDE terms. Any eventual modification of the MQL4 IDE terms that establishes MetaQuotes' right to charge royalties is subject to a three (3) months' prior notice thereof. Your continued use of the MQL4 IDE shall constitute Your acceptance to be bound by the terms and conditions of the revised MQL4 IDE terms."

What does it mean by above statement .Does MQL Developers needs to pay any fees for compilation or any royalties.